What is Bitcoin? A Beginner's Guide
- Perry Gowdy
- Apr 10
- 21 min read
Updated: Apr 14
Howdy y'all, and welcome to this detailed exploration of Bitcoin, designed for those eager to understand what the heck Bitcoin is and how it works. This post will guide you through how Bitcoin operates, break down the complex pieces of the tech, and explain some of the buzzwords you might've heard surrounding it. We’ll cover its core mechanics and some of the properties that make it special. My goal is to equip you with a strong foundation in the "what" so that you'll be ready for the follow-up post explaining the "why." This isn’t about persuading you of Bitcoin’s value; it’s about understanding what it is and how it works.
At the end, I'm going to drop a ton of links to great resources that dive deeper into the technical bits, cover more topics about Bitcoin’s mechanisms, or just explain it in a different way. Learning takes repetition. It took a while before Bitcoin finally "clicked" for me, so don’t get discouraged if you finish this article and still have questions. Let’s get after it!
Table of Contents:
Bitcoin: The Global Ledger
Bitcoin was introduced in 2008 by an anonymous figure (or group—their true identity is still unknown) known as Satoshi Nakamoto. In a scientific whitepaper titled "Bitcoin: A Peer-to-Peer Electronic Cash System," Satoshi shared the concept of Bitcoin for the first time. He did this through a cryptography mailing list hosted at metzdowd.com, a sort of newsletter for technologists focused on digital privacy and cryptography. Satoshi birthed Bitcoin from the anger and tumult that the Great Financial Crisis caused millions of people around the world. He was enraged by government bailouts of big banks and instead wanted to empower people with financial sovereignty. Satoshi's motivation runs deep, and the reasons for creating Bitcoin go even deeper, but let’s not get too off course.
At its essence, Bitcoin is just a big, global record. Think of it this way, a big piece of paper that records every transaction anyone in the world makes in Bitcoin. Really, at its core, it’s that simple. Satoshi’s whitepaper (the document he published explaining Bitcoin) title was on the nose: "A Peer-to-Peer Electronic Cash System." "Peer-to-peer" (P2P) just means transactions happen directly between users over the internet, bypassing banks or payment processors. It also suggests that the users are equals, hence "peers." "Electronic Cash System" means a digital way to transfer money, and in this case, he called that money Bitcoin. It’s a global currency where you can send value, say the equivalent of $10, to someone -- anyone -- across the world, near instantly. That’s Bitcoin.
The Bitcoin Network
Now we have to get a little technical. The global record I mentioned is updated and managed by the Bitcoin network through the blockchain. The Bitcoin network is the pen, the blockchain is the paper. I’ll get to what the blockchain is in just a minute, but for now, let’s focus on what the Bitcoin network is.
The Bitcoin network is a vast, global system of computers that work together to keep Bitcoin running. These computers are operated by everyday people who choose to install and use the Bitcoin software on their devices. This software is completely safe to run, has very humble hardware requirements, and you don't need any Bitcoin to run it. Each computer choosing to run this software is called a node, a technical term for a computer that’s part of a larger network running a specific program -- in this case, the Bitcoin software.
Think of the Bitcoin network as a big, shared workspace where all these nodes collaborate. They don’t rely on any central authority, like a bank or a company, to manage things. Instead, the nodes talk to each other to make sure everything in the Bitcoin system is accurate and secure; they rely purely on the Bitcoin software’s code. For example, when someone sends Bitcoin to another person, the nodes check the transaction to confirm it’s valid, like making sure the sender has enough Bitcoin to spend. Once verified, the transaction gets added to a shared, global record that all nodes on the Bitcoin network receive, keeping them up to date on the latest transactions. This setup, where no single entity is in charge, ensures the Bitcoin network is open to anyone who wants to participate by running the software, making it a truly global and community-driven system. Seriously, a technical person can visit this link (https://bitcoin.org/en/download), download the Bitcoin client, and start participating as a node in the Bitcoin network with just a little setup.
How does this all operate so smoothly, though? What happens if something goes wrong, say a node gets hacked or two nodes disagree on a recent transaction? How do you deal with disputes? The answer has two parts.
Open Source and Its Resilience
First, when Satoshi created Bitcoin, he committed to making the project completely open source. Open source, in the context of software, means anyone is free to contribute to the code that makes up the software. It also means all the software’s code is completely transparent and viewable by anyone. This leads to a level of scrutiny that’s impossible for a company that owns software and keeps it private. There are simply more eyes on it and more people willing to contribute to the codebase. Traditionally, this results in more resilient code with fewer problems.
During its entire lifespan, Bitcoin has only had two incidents that have caused slowdowns in the network, both occurring in its infancy. The first took place in 2010 and was called the Value Overflow Incident. Simplifying a bit, the incident basically amounted to a bug that was obvious once caught and trivial to fix. At the time, there were few users of Bitcoin, so it was quite easy for Satoshi to make the code change and get all nodes to agree. It was caught and corrected in 6 hours and 20 minutes, and did not halt the network from processing transactions completely.
The second, occurring in 2013, didn't really have a name, but essentially caused Bitcoin to split into two different versions. It took about an hour for enough evidence to accumulate to fully verify that Bitcoin had split into two different versions. After that, the first proposal to fix the code was suggested 16 minutes later and developers reached agreement on that solution in under 30 minutes. All in all, only about two hours had elapsed from the beginning of the problem occurring to the solution being proposed and executed. Additional time was needed for the entire Bitcoin network to pick up these changes and validate that they were on the correct version. After that, the other branch was forgotten and forever invalidated. The entire disruption lasted 8 hours and 27 minutes in total, and like the Value Overflow Incident, did not halt the network from processing transactions completely.
The resilience of the Bitcoin network is nearly unbelievable when held to the standards of other large computing networks around the world. It's also worth mentioning, but not diving into, the fact that the Bitcoin network has been attacked thousands of times by ill-intended hackers and groups of hackers, but the network has NEVER been disrupted by a hack. Since its inception, Bitcoin has had no complete outages. It's undoubtedly one of the most reliable computer networks to ever exist. You can view the uptime tracker and dive deeper into the two outages here: (https://bitcoinuptime.com/).
How does Bitcoin’s code get updated, and what keeps it so reliable? Because it’s open source, anyone can propose a change, whether it’s a new feature or a fix, but it’s a very structured process. Suggestions start as Bitcoin Improvement Proposals (BIPs), detailed documents shared with the community. These proposals are discussed openly by volunteers, developers, users, and thought leaders on forums, Twitter (now X), mailing lists, and more. The community reviews each BIP carefully, testing it to ensure it’s safe and beneficial. Only after widespread agreement is reached does the change get added to Bitcoin’s software, a step that can take months or even years. Not every computer, or "node," running Bitcoin has to adopt these updates, though. Nodes can stick with the old rules if the change is optional, like an improvement that doesn’t break compatibility. This slow, consensus-driven approach, combined with the freedom for nodes to choose, ensures Bitcoin stays stable and secure, avoiding rushed changes that could disrupt the network.
The Blockchain
Now, let’s talk about the blockchain, or "the paper" as I called it earlier. The blockchain is the heart of how the Bitcoin network keeps and updates that global record I mentioned, and it’s the second reason Bitcoin stays so secure. Imagine the blockchain as a giant, shared notebook that every node in the Bitcoin network has a copy of. Every Bitcoin transaction, like sending $10 worth of Bitcoin to a friend, gets written down permanently and cannot be changed. This shared notebook is not kept in one central place, like a bank’s vault or under a mattress; instead, a perfect copy is spread across all those thousands of Bitcoin nodes worldwide. Again, every single node has a copy of that notebook.
I’m going to simplify for a moment but will circle back right after. The next paragraph explains Bitcoin mining, but I think understanding the purpose of mining first makes the process easier to grasp.
When you send Bitcoin, nodes work together to check that transaction, making sure you have enough Bitcoin and haven’t already spent it somewhere else. Once they agree it’s legitimate, the transaction gets added to a new section, or "block," in the notebook. A block is actually a large number of transactions grouped together, typically around 1,500 to 2,500 transactions. That block connects to all the previous ones, creating a chain of records -- hence, blockchain. The blockchain updates by blocks rather than single transactions because it’s much easier to coordinate. It’s simpler to update thousands of computers with blocks of data every few minutes than with single transactions every few milliseconds. Imagine, even at a smaller scale, you were tasked with writing down phone numbers for 100 people. How frustrating would it be if someone kept handing you scraps of paper with one digit at a time? You’d much rather get all 100 numbers on a big sheet of paper at once so you could copy them efficiently. The same is true in computing.
These blocks that make up the blockchain are connected through a complicated cryptographic algorithm, or "hashing function" (SHA-256), that makes verification of previously added blocks nearly instant. Changing even one transaction in that chain of blocks would invalidate the entire blockchain up to that point. It would mean rewriting the chain from the corrupted block to the current block on the majority of computers that make up the Bitcoin network, a task virtually impossible without everyone noticing and agreeing. Furthermore, as more transactions are added to the blockchain, it becomes harder to change. The more blocks there are, the more computing power is needed to alter all the records that come after the corrupted block. Bitcoin only gets more secure with time.
Now, let’s look at a practical example. Say a person named Alice tries to get more Bitcoin through shady means. Alice runs a Bitcoin node and decides to trick the network by changing her copy of the blockchain to say she never spent 5 Bitcoin she sent to Bob last week, hoping to use those same 5 Bitcoin again to buy something from Charlie. Here’s why that won’t work. When Alice tries to send those 5 Bitcoin to Charlie, her node she's running might say it’s fine, but every other node on the network (like Bob’s, Charlie’s, and thousands more) still has the original record showing she already spent them. The network compares notes, and since Alice’s version doesn’t match the majority, her transaction gets rejected. To succeed, Alice would need to convince over half the network’s nodes, tens of thousands of them, to rewrite their records too, all at once. That’s a massive task requiring more computing power than she could ever hope to control (and more than any entity in the world could come close to controlling), and the rest of the network would spot her attempt instantly.
This is why the blockchain’s design, spread across so many independent nodes, keeps Bitcoin’s transactions secure. It's also why Bitcoin is decentralized and immutable. No authority or governing power validates each transaction; the network, all the people choosing to run a Bitcoin node, handle that job. The word "immutable" just means permanent, or "cannot be changed." Because it’s so hard (theoretically impossible with today’s tech) to change a recorded Bitcoin block, people often say Bitcoin transactions are immutable.
Bitcoin Mining
The whole point of Bitcoin mining is to add new blocks to the blockchain. That’s the most important thing to understand about it. If you only take one piece of info from the text you’re about to read, make it that: the purpose of Bitcoin mining is to add new blocks to the blockchain. Individuals or organizations that take part in Bitcoin mining are the ones who propose exactly which new blocks should be added to the blockchain. How does this happen? Through a mechanism called Proof of Work (PoW).
PoW is a competitive process where participants, known as miners, use computing power to solve complex math problems about every ten minutes. The winner of this competition (the competition being solving that complex math problem) earns the right to add the next block of transactions to the blockchain and gets some newly minted Bitcoin for their work. To solve this math problem, miners throw out trillions of guesses per second, trying to find a random number within a massive range of numbers. The range is so huge it’s tough to wrap your head around, bigger than the total grains of sand on Earth, many times over. Over time, miners acquire more and more computer hardware to make more guesses for each problem, boosting their odds of solving it. At the same time, miners with less funding for gear still have a shot at solving it since it’s really just guessing numbers. It’s as close to fair as it might get.
When a miner solves the problem, they propose the block be added to the blockchain. The clever part about this math problem is that while it’s super hard to solve, it’s trivial to verify once the answer is found. The nodes on the Bitcoin network then decide together if the block is valid. If more than 51% of them agree it is (in other words, they all agree the solution to the math problem is correct), it’s added to the blockchain, the miner gets 3.125 Bitcoin, and the next math problem starts. If not, the block is tossed out, and the Bitcoin network waits for the next proposed block to check.
That’s the straightforward explanation of the process, but there are a couple wrinkles worth mentioning: difficulty adjustment and reward adjustment.
Remember I said these math problems are solved about every ten minutes? That’s by design. Part of the Bitcoin code includes a difficulty adjustment variable that changes every two weeks so the math problems always take roughly ten minutes to solve. By using statistics to measure how fast the problems were solved over the past two weeks, and comparing that to the computing resources used, the algorithm adjusts for difficulty, making the range of numbers bigger or smaller.
Imagine you’re in a room with 100 people. You’re all trying to guess a number between 1 and 1,000, and whoever guesses it gets $500. Well, with 100 people guessing random numbers, you quickly realize that number gets guessed in 5 to 10 seconds. It doesn’t make for a very exciting competition, so you adjust the number to be between 1 and 1,000,000. Now, it takes people 30 to 60 minutes to guess it, and it gets boring. Word spreads about your competition (and the prize money), and 1,500 more people join in. Now you have 1,600 people trying to guess a number between 1 and 1,000,000, and it’s taking, on average, around 10 minutes each time. That’s difficulty adjustment.
In the Bitcoin network, this 10-minute timing is key because it gives all nodes enough time to update their records and verify that transactions are valid. Spacing out the blocks lets all the nodes catch up, double-check the block, and ensure everyone’s copy of the blockchain matches. It makes it much harder for anyone to tamper with the system and get away with it.
Then there’s reward adjustment. First, it’s important to know that only 21 million Bitcoin will ever be created. Period. That’s the hard, code-enforced, cap. The only way this could change is if the Bitcoin network voted to alter the code, but there’s little reason to do so. This 21 million limit was set to fight inflation, a sticky issue with non-asset-backed currencies and a topic for another article.
Reward adjustment is about changing the amount of Bitcoin given to miners for adding a new block to the blockchain (solving that tough math problem). When Bitcoin first rolled out to the public, the reward was 50 Bitcoin per block. But the code has a variable that cuts that reward in half every 210,000 blocks. This event, called the halving, happens roughly every four years.
Both reward adjustment and difficulty adjustment were built into Bitcoin to ensure the network lasts. In the early days, when Bitcoin was a small project with few users, it was key to hand out lots of Bitcoin since their value was low and spreading awareness mattered more. As the project grew and more people started holding Bitcoin, it became important to slow down the supply to maintain value. The creators wanted to avoid inflation. They didn’t want the supply to spike and make early mined Bitcoins less valuable. Right now, miners get 3.125 Bitcoin for every block they add. The next halving, set for mid-April 2028, will drop that to 1.5625 Bitcoin. There are nearly 19.9 million Bitcoin already mined (about 94.5% of all that will ever exist) as of 2025, so the inflation rate each year is super low. Check out this great website showing Bitcoin in circulation on a graph: (https://bitbo.io/how-many-bitcoin/#:~:text=How%20Many%20Bitcoins%20Are%20There%20Now%20in%20Circulation%3F,historical%20amount%20of%20bitcoins%20here).
As for difficulty adjustment, it was added to handle the evolution of computing power. If the initial range of numbers for the math problem was set and never changed, then as computers got better, that problem would be solved faster and faster until it took just milliseconds. The Bitcoin network couldn’t keep up if thousands of blocks were proposed every few seconds. Difficulty adjustment lets the network scale as computers improve.
But who is really doing the mining? Well, current estimates in 2025 put the number at somewhere a little over one million unique individuals. There are over 20+ major companies worldwide dedicated to Bitcoin mining, with the largest three being Marathon Digital Holdings, Riot Blockchain, and Core Scientific. In other words, it's a small percentage of Bitcoin users. For the most part it's large companies, big groups of people pooling their resources, or the occasional Bitcoin mining hobbyist.
That’s the foundation of how Bitcoin works! There’s just one more section we need to cover for a full picture: how you, the user, actually send Bitcoin to others.
Wallets and Keys: Bitcoin Ownership
Bitcoin isn’t stored in a traditional way; it’s not in a vault or a real-world piggy bank. It’s just numbers on the blockchain. You, the user, access the Bitcoin you own through wallets. A wallet is a piece of software (or hardware) that manages two critical parts: a public key and a private key.
When a new wallet is created, it makes a new public key. This public key is a randomized string of numbers and letters that uniquely identifies the wallet. When someone wants to send you Bitcoin, you give them this public key, often called an "address." The blockchain doesn’t know your wallet address exists until you receive Bitcoin for the first time. Only then does your address get added to a block on the blockchain, and the Bitcoin network becomes aware of it.
A private key is also created when you make a new wallet. This is another long string of numbers and letters, but it’s mathematically tied to the public key. This is the key you keep secret to prove to the Bitcoin network you own the wallet. It "unlocks" the wallet so anyone with the private key can use it.
Imagine you’ve got a locked mailbox at the end of your driveway with a number on it, like “123 Main St,” that anyone can see and use to send you letters. In other words, it has your address. In Bitcoin, that’s your public key, or wallet address, a unique string of numbers and letters, like “1A2b3C,” that you share when someone wants to send you Bitcoin. Anyone can drop mail (Bitcoin) into that box using just the address, and it’ll show up on the blockchain once they do; the Bitcoin network only knows your “mailbox” exists when something arrives. Now, inside your house, you’ve got a special key that unlocks your mailbox so you can get the mail out. That special key is your private key, another string of characters tied mathematically to your public key, that you keep hidden. Only you can use it to “unlock” your mailbox (wallet) and read the mail (spend the Bitcoin inside). Plus, this mailbox has a lock that can’t be picked or opened any other way. Only the single key you hold can open it, guaranteed mathematically by the Bitcoin network.
As for wallets, there are two main types: software wallets and hardware wallets (also called hot wallets and cold wallets). A software wallet (hot wallet) is created digitally by a piece of software. These are often seen as less secure because the software stores your private key on the device you use. So if your device gets hacked or stolen, someone could access your Bitcoin wallet. Software wallets are often called hot wallets because by virtue of always being connected to a network (via your device), so they're always on, or "hot". There are tons of software wallet providers (Bitcoin Core, Exodus, MetaMask, Electrum, and more), some using open-source software and many vetted over the past decade.
Hardware wallets (cold wallets), on the other hand, are physical devices, like a USB stick, that offer better security. Again, tons of companies sell hardware wallets (Trezor, Ledger, Jade, ColdCard, etc.), so there are many to choose from. When you set up a hardware wallet, it generates public and private keys inside the device itself, and that private key never leaves it. Whenever you want to send someone Bitcoin, you plug the hardware wallet into your computer and approve the transaction through the device. This way, your wallet is only exposed when you’re sending Bitcoin. This is also why they're called cold wallets. For 99% of the time, it’s stored safely somewhere in your home, and hackers have no way to get at it, so it's "cold".
Sending Bitcoin
Alright, we’ve learned how the Bitcoin network works and how it ties to the blockchain. We’ve covered mining and the decentralized and immutable properties it brings, and we’ve seen how Bitcoin is stored on the blockchain through wallets and how they’re created. But how do you actually send Bitcoin?
A primary feature of all wallets, beyond just providing a public and private key, is the ability to broadcast a Bitcoin transaction to the network. All of them facilitate you sending and receiving Bitcoin from other people! This connects back to Bitcoin mining and those blocks that make up the blockchain.
Whenever you send Bitcoin to someone else, your wallet signs it with your private key and sends the transaction to the Bitcoin network. The network checks that your wallet has enough Bitcoin to send and that you haven’t already spent it elsewhere. Then your transaction gets added to the next available block, those same blocks miners hope to add to the blockchain for a reward. "Next available" just means the next block with space. As I’ve said, most blocks hold about 1,500 to 2,500 transactions. This comes from a size limit coded into the Bitcoin software. It ensures users don’t need really expensive hardware to run the software and keeps the blockchain from growing too large to store on an average person’s computer.
After your transaction is sent to the Bitcoin network and the block it’s in gets added to the blockchain by a miner, it’s done! Your transaction is permanent. The blockchain will always show you sent that Bitcoin to another address. The record is open and fully transparent. Anyone can go review that the transaction happened, forever.
Why Bitcoin?
Wait, Perry, but I thought you said this was all about the "What"? Now you're going to explain the "Why"? Well, the "Why" is important, and you've come this far! I'm also just going to give you the briefest of summaries while the "What" is still so fresh in your mind. We'll save the deep dive for another article, as promised.
First and foremost, Bitcoin was created to combat inflation and currency debasement by governments and banks. Currency debasement is what happens when the value of a currency becomes less over time. Think about how in the 1950s you could buy a burger and soda for $.20 while now $.20 won't even buy you a piece of bubblegum. This can be very bad for the average person because it disincentives them from saving, and it erodes their purchasing power. It compounds if wages don't also increase to match or exceed inflation, a phenomenon that is most often the case! Over time, it dramatically widens wealth inequality as wealthy folks are able to buy assets (property, stocks, commodities, bonds) and protect their wealth from diminishing.
The second reason Bitcoin was created is partially intertwined with the first, but is important enough to be separated. Bitcoin was created to be a truly neutral financial system that is not centralized in its control by any nation, state, bank, or organization. As of now, the US dollar is the world reserve currency. In order to buy oil internationally, it's basically a requirement (~80% of global oil trade is done this way) that you do so in dollars. This is a great deal for the US, but the rest of the world isn't quite as excited. Bitcoin acts as a completely neutral, democratic, decentralized finance system that ANYONE can participate in. There's no one pulling the strings to give an advantage to specific countries or companies, it's truly neutral.
Summary
The Bitcoin network is made up of thousands of computers (nodes) that run the Bitcoin software. Anyone can join the Bitcoin network as a node.
The Bitcoin software is open source. Anyone can propose a change to the code, and if most of the Bitcoin community agrees, it can be changed. This process is tough and rare, part of what makes Bitcoin decentralized.
The Bitcoin blockchain is managed by the network. Each block has about 1,500 to 2,500 transactions between users. The blocks are linked together in a chain, verified by a complex computer algorithm. Once a block is added, it’s nearly impossible to change, making Bitcoin immutable.
Miners use computer hardware to guess random numbers, trying to solve a math problem. The first miner to solve it adds the next block to the blockchain and gets new Bitcoin as a reward. The network checks that the block is valid. This is called Proof of Work.
The network adjusts to last: every two weeks, the math problem’s difficulty shifts to keep blocks at 10 minutes, no matter how many miners join. The reward for miners also halves every four years (next in 2028, down to 1.5625 Bitcoin) to control supply.
Only 21 million Bitcoin will ever exist, hardcoded to fight inflation. With about 19.9 million already created in 2025, new Bitcoins come slower due to halving events. The target year for the last Bitcoin to be mined is 2140.
Bitcoin lives on the blockchain, not in your pocket or anywhere physical, and you access it with a wallet. A wallet gives you a public key (your address to receive Bitcoin) and a private key (your key to spend it), like a mailbox number and its key.
Your wallet signs a transaction with your private key and sends it to the network. Nodes check it, miners pack it into a block (about 1,500 to 2,500 transactions big), and once it’s on the blockchain, it’s permanent and public for all to see.
Bitcoin was created to combat inflation and currency debasement. It was also created to serve as a neutral, democratized, global financial system with no government, state, or company controlling it.
Hopefully, this was a good starting point for you. If you had no clue what Bitcoin was, I hope I at least gave you some solid topics to explore and maybe even a big, general picture of how it works. As a technology, many claim Bitcoin’s power comes from its simplicity. Sure, it uses fancy computing algorithms and ideas to do its thing, but when you piece it together and cut out some jargon, I think it’s something anyone can understand and appreciate. As promised, I’m dropping a bunch of links below for more learning, but don't forget to check under "Resources" in my website -- those links are for general crypto, not just Bitcoin, but they could also be quite useful. There are so many amazing resources out there that I’m sure I won’t cover even close to all of them. If you want specific crypto coaching or to dig deeper into anything, don’t hesitate to reach out. Thanks for reading!
https://bitcoin.org/bitcoin.pdf - The original white paper released by Satoshi Nakamoto. This will feel INCREDIBLY dense to beginners. If you're having trouble understanding it, circle back to it after you've used some other resources. https://learnmeabitcoin.com/ - Probably the single most helpful resource for truly understanding Bitcoin. Walks through all parts of Bitcoin, technically or non-technically, with plenty of amazing graphs and diagrams.
https://littlebitcoinbook.com/ - I haven't actually read it, but I've heard really great things. I think it could be a great place to start if this article is one of your first forays into Bitcoin.
https://www.youtube.com/watch?v=lHipE05v4jg - Coin Bureau's guide to how Bitcoin mining works. Much more in-depth than what I was able to cover here. They release a ton of great content.
https://www.lopp.net/bitcoin-information.html - Website with an unreal number of Bitcoin resources. Jameson provides good resources for every topic under the sun: taxes, governance, how to explore the blockchain, developer tools, adoption, security, etc.
https://bitcoin-resources.com/ - More focused, but far less encompassing, this website provides some good books to read, videos to watch, and podcasts to listen to.
https://wtfhappenedin1971.com/ - I hesitate to include this, as it's to do more with why many people believe Bitcoin is the answer to our monetary struggles, but it's such an interesting site that I have to. It shows all of the wild statistics that emerged after going off the gold standard.
https://bitcoiner.guide/qna/ - I like this because it's in question and answer format. A lot of great answers to commonly asked questions, including some myths surrounding Bitcoin that are pretty fascinating.
https://nakamotoinstitute.org/library/ - For those wanting a seriously deep dive. This has all of the books related to Bitcoin/cryptography. Some of the books here are only vaguely related to Bitcoin, so don't just pick something at random to read (unless you're just a curious person, of course).
https://vijayboyapati.medium.com/the-bullish-case-for-bitcoin-6ecc8bdecc1 - Incredible article that dives into the economics of Bitcoin. Leans much harder into "Why?" then "What?".
Thanks Perry! I never really understood Bitcoin until reading this!- Tara