Most explanations of blockchain lose people by the second sentence. Decentralized, Immutable, Distributed, Trustless. Four large words and no image in your mind. If you entered how does blockchain technology work simply into a search bar, and left feeling as confused as you had when you first entered the query, you’re not to blame.
The simple version is: A blockchain is a common record book, where thousands of computers store copies. The new entries are added to blocks of data, a digital fingerprint of the previous block, and the computers must confirm each block in turn before it is added. If an old entry is altered, the fingerprints no longer align and no one can sneak in and alter the past.
Well, that’s it in a nutshell. The rest of this guide walks through each moving part, one at a time. At CrypStudio, we interact with blockchain data daily, and we’ll walk you through it as you would a new friend who is just about to send crypto for the first time.
Picture a Notebook Everyone Owns
Suppose that 20 friends share the expenses of a summer cabin. No one wants to be responsible for the only copy of what has been paid for, so each friend has her own copy of the same notebook. When someone purchases groceries, they say it to the group, everyone makes sure it totals up, then a line is written in each person’s copy.
Now add two rules. Each page concludes with a short code that summarises what has been written on the page and each following page begins by copying that code. When it’s time for a new page, only after it has been agreed upon by a majority of the group is it counted.
Attempt to cheat in that scenario. Say Tom adds an old grocery note to his journal which he has altered. His page code is no longer the same as the one that has been copied at the top of his next page, and his notebook doesn’t match up with the other nineteen. He would have to rewrite every page and all subsequent pages in more than 1/2 the notebooks at a faster pace than everyone else piles new pages onto them.
Good luck with that.
Replace the friends with computers and the notebook with a database and you’ve got a blockchain. If you google what blockchain technology is, you will get dozens of definitions that can be summarized as follows: blockchain is an unchangeable, verifiable, shared record. It is typically filed under distributed ledger technology (DLT) by banks and regulators. Ledger is merely an old term for a record book. Distributed refers to the fact that the copies are not on a single company’s server.
There’s just one tiny footnote: all blockchains are DLT, but not all DLTs are based on blockchain technology. That chaining is clever, let’s take a look at how it’s done.
The Five Pieces That Make It Work
All public blockchains, including Bitcoin and any new one that has been created in the past week, share a few common components.
Blocks are the pages
A block is a collection of recent transactions that have a small block header at the top. The header includes a summary fingerprint for all transactions in the block, and a fingerprint of the previous block. Developers call that summary the Merkle root, after the computer scientist Ralph Merkle. The header also includes a number, called the nonce, on proof-of-work chains, which will be important in a minute.
The network size and speed depend on the network. Every 10 minutes, there is a new block in Bitcoin that contains several thousand transactions. Ethereum’s target is to process one transaction every 12 seconds.
The fingerprints are called hashes
Those fingerprints are generated by a cryptographic hash function, a small piece of math that produces a fixed-size string of letters and numbers from any input (a word, a photo, and so on, even an entire block). One that’s used by Bitcoin is called SHA-256. Observe the change in the word when you change one letter:
hello world → b94d27b9934d3e08a52e52d7da7dabfac484efe37a5380ee9088f7ace2efcde9
Hello world → 64ec88ca00b268e5ba1a35678a1b5316d212f4f366b2477232534a8aeca37f3c
If you put one capital letter, then it will be unreadable. That is, the input always gives the same output, the tiniest change brings about an entire mess, and the output cannot be used in reverse to reconstruct the original fingerprint. Try it with any free online SHA-256 tool. It only takes 10 seconds, and typically that’s when everything is finally coming together.
The chain is fingerprints pointing backwards
This is where the ‘chain’ comes from. Each block has a header that contains the fingerprint of the previous block. It uses blocks 900,000 to 899,999, which point to 899,998, back to the first block.
Now tamper with a transaction in an old block. That block’s fingerprint changes. The previous block’s fingerprint in the next block is now wrong, which alters the fingerprint of that next block, which breaks the next block, and so on. Each edit spreads through the subsequent blocks and all good (honest) computers on the network see the mismatch immediately.
Blockchains are so popular for being immutable. It’s more like tamper-evident. You can try to change history. There’s no way you can deny you did.
Nodes are the people holding the copies
The computer that holds and verifies the ledger is referred to as a blockchain node. A full node will download the whole history and re-check each rule by itself, rather than relying on anyone, and is available for everyone to run in a public network. The first sync will always be remembered if you have ever set up one. Bitcoin has already accumulated many hundreds of gigabytes of history, and processing the full history of Bitcoin transactions can take a few hours to a few days on a home computer.
That’s the independence bit, and the point. There’s no master copy sitting in a data center somewhere. Blow up a major part of the nodes and the other ones continue.
Keys are your signature
Your crypto wallet doesn’t actually store coins. The coins are permanently stored on the ledger. What your wallet stores is a pair of public and private keys. The public side is converted to your address, which you can give out as an account number. The private key is used to sign your transactions, creating a mathematical signature that is evidence that the owner has agreed to a payment without ever revealing the private key.
Nodes verify the signature prior to accepting anything. This is what it means that if you have the private key or 12/24 word recovery phrase that can generate it, you have the funds. No forgot password option. Think of that, it will be there at our safe place.
Follow One Payment From “Send” to “Confirmed”
Take an audience of people and ask them what is blockchain and a majority of them will begin discussing Bitcoin’s price. It’s more useful to follow a single payment. In Chicago, Sara wishes to send 0.01 BTC to her brother, Adam, in Manila.
Step 1: Sara’s wallet builds and signs the transaction
She pastes Adam’s address, types the amount and picks a fee. Her wallet signs a short message it puts together, which effectively contains ‘moved 0.01 BTC from this address to that one’. It’s only applicable to this exact text message, so nobody can use the same signature to send a different amount to a different address.
Step 2: checking it by the network
The signed transaction is sent by a few nodes to their neighbours and on to others. It is spread throughout the network within a few seconds. All nodes execute the same tests. Does the signature appear as a valid signature? Does Sara actually have 0.01 BTC that hasn’t been used yet? When the answers are yes, the transaction sits in a holding area called a mempool, where all the pending transactions are placed.
Step 3: It is then put inside a block
On a proof-of-stake system, anyone interested in mining (or validators) has the chance to select transactions from the mempool to include in their next block, and these transactions are typically the ones with the biggest fees. That is why the fees in a payment can be stingy, and a payment can be unconfirmed for hours when the network is busy
Step 4: The network comes to an agreement on the block
The final step is for the rest of the network to agree to Sara’s block, which is required by their rules of agreement. Most guides gloss over this part so it is given a section of its own below.
Step 5: Copy and Chain the Block
Once accepted, the block is added to the previous block’s fingerprint, and each node copies it to its own fingerprint. The payment has been added to the blockchain, with one confirmation on Adam’s wallet and each block on top being another confirmation. A large sum of money is considered settled after six Bitcoin confirmations, which takes approximately one hour. There’s a lot of work involved in reversing it at that point.
None of the banks handled the money. There was no need for anyone to be open for business. In non-technical terms, the answer is: strangers verify the calculations, they agree on the order in which they do so, and everybody writes down the same answer.
How Thousands of Strangers Agree Without a Boss
The challenge that a blockchain needs to solve is quite simple to express. Digital money is just data, and data can be copied. What prevents Sara from sending 0.01 BTC to Adam, and then 0.01 BTC to someone else a second later? This is known as the double-spend problem and is why previous digital cash systems had to be based on a central organization keeping track.
That company is replaced by a consensus mechanism, a set of rules that are agreed upon by all nodes and executed to determine which block should be added to the chain and which is the true history. Two designs dominate.
Proof of work: spend electricity to earn the pen
Bitcoin uses proof of work. Miners race to mine a block that contains a nonce in the block header which produces a fingerprint with a long string of zeros. There’s no shortcut. The only way is to guess and modern mining machines make trillions of guesses per second. The first miner to discover a correct answer publishes the block, other miners immediately check it and the winner receives the new bitcoins, which are now 3.125 BTC per block since the halving in April 2024, and the fees of all of the transactions within it.
It changes the difficulty level every 2016 blocks, approximately every two weeks, ensuring that the new blocks are added to the network at approximately 10 minutes per block regardless of the amount of mining power that joins or leaves. An attacker would have to have more power to guess than all the other nodes in the network. It’s the one for which we’re all famous: the 51% attack. On Bitcoin, it would be a huge investment of hardware and electricity. Small PoW coins, indeed, are a real threat in 2019-2020, ETC experienced multiple such assaults.
Proof of stake: put money on the line
Elimination of electricity in favour of stakes. In Ethereum, every validator puts 32 ETH or more into their stake. A protocol randomly selects one of the validators to propose a block, after which a committee consisting of other validators votes on the proposal. Abide by the rules and there is a reward. Attempt to cheat (such as signing two different blocks) and part of your stake is destroyed and you are ejected from the network. This is known as slashing and is a good motivation for good behavior.
The Merge, an upgrade on Ethereum, reduced its energy consumption by approximately 99.95% and shifted from mining to staking on September 15, 2022.
So which one is better?
The debate between proof of work vs. proof of stake has been going on for roughly 10 years, and in all honesty, they both work. The longest-running, and one of the simplest security stories is proof of work. Proof of stake requires a very small amount of energy and blocks are finalized much quicker. Our opinion is that the importance of the model is less than its network size. To attack a large, active chain is challenging with either of the two designs. A small chain can not keep any large chain.
Beware of new projects that promise their own hybrid consensus, but don’t give you a link to a live network or public code. As we discussed in our Etherions Faston Crypto breakdown, that’s exactly what you see all the time: a large whitepaper has a lot of promises and nothing on the blockchain to substantiate it.
Not All Blockchains are Public
Blockchains come in four categories and it is the access of all but one of them that differs.
Permissionless chains are public chains, such as Bitcoin, Ethereum and Solana. They are readable by all, can be used to send transactions, or to run a node. Enterprise frameworks like Hyperledger Fabric were created for this purpose, whereas private chains are managed by a single organization, which rules on who can participate. Consortium chains distribute power among the companies. This is evident in trade finance and shipping, where, with no single company in complete control of the record, there is a need for a shared record. Hybrids combine both, retaining privacy for some data while providing a guarantee of it on a public chain.
A potential drawback is that if there is only one company that owns all of the nodes, you have to trust that company, which is what a blockchain was supposed to eliminate. Sometimes, that is OK, as in the case of business partners who only need to be able to reference an audit trail for themselves. Just don’t let the word blockchain on a brochure do the convincing.
When the Ledger Starts Running Code
Bitcoin’s ledger primarily records the ownership of which coins. Ethereum, which was launched in 2015, added something larger: Programs stored on the chain that will run exactly as written whenever their conditions are met. These are smart contracts. The concept was described by computer scientist Nick Szabo, who first used the term in the 1990s, in a comparison to a vending machine. Insert the correct coins, click a button and collect your snack. No clerk needed.
This code now drives stablecoins (tokens designed to represent a specific currency, typically the USD), lending platforms, token swaps, NFT marketplaces, and tokenization of classic assets such as Treasury funds. It’s also where a lot of money goes down the drain. It is so nice to have code that cannot be changed until someone has found a bug in it, then it is permanent too. Audited code, with history, wins over a glitzy new project with guaranteed results any day of the year.
Bitcoin Is One Blockchain, Not the Blockchain
Sitting at the intersection of blockchain and Bitcoin, it seems logical that the mix-up has happened, though it’s the ‘old-fashioned’ Bitcoin that’s still the popular one. Think of email and the internet. The internet is not one thing that you can do online, that’s email. Bitcoin is one application of blockchain technology, and thousands of other blockchains now operate on their own terms, have their own tokens, and serve their own function.
The concepts listed below are not new, but are somewhat older than some people realize. Already in 1979, Ralph Merkle described his hash trees. In 1991, researchers Stuart Haber and W. Scott Stornetta published a solution that would make it impossible to backdate digital documents, and a company began printing a hash of its records in The New York Times classified ads in 1995. Then, on October 31, 2008, someone used the pseudonym Satoshi Nakamoto and published a nine-page Bitcoin whitepaper, incorporating Hashcash-style proof of work and a reward for strangers who maintain the ledger. The first Bitcoin block was generated on January 3, 2009, and inside the block you’ll find a bank bailout newspaper headline.
In case you desire the thought directly from the source, the whitepaper is worth an evening. It’s more readable than its reputation.
Why Anyone Can Look Up Any Wallet
In the public chain, all the operations performed are recorded and visible to everyone. Open a blockchain explorer, enter an address, and you will be able to see its balance, all the payments in and out, and when they were made. No login. No permission.
That is surprising to those who think that crypto is anonymous. It’s pseudonymous. There are no names attached to addresses, but the flow of money can connect addresses and if one of them comes into contact with an exchange that verified your identity, the trail can lead back to you.
This openness also makes it possible to have crypto safety tools. The public history makes it easy for anyone to keep track of how long an address has been collecting funds from people who have reported scams or accepting funds via mixers. A signal such as this is used by analysts to determine a rating for the risk involved, similar to the fraud scores already used by banks and payment providers. It’s the same public trail our scanner reads when it flags a wallet as suspicious.
Is It Really Unhackable?
Is blockchain hack resistant? The ledger itself, very rarely. Rewriting history for a large chain requires having the combined mining power or stake of the network itself and that’s never happened with Bitcoin or Ethereum. Close to all of the hacks that make the news affect something that rests upon the chain top.
The Ronin bridge suffered more than a $600 million loss back in 2022 after hackers obtained five of the nine keys to approve withdrawals. Bybit, a leading cryptocurrency exchange, suffered approximately $1.5 billion in losses in February 2025, primarily in Ether, as a result of the exploitation of its web interface’s multi-sig wallet service. The signers believed that they were approving a standard transaction between the exchange’s wallets. No one tampered with the math. The users who were going through the transaction were presented with a fake screen and the blockchain performed according to the instructions given.
Everyday users run into smaller versions of the same trick. Bogus support agents requesting the recovery phrase. Platforms that allow you to withdraw once, and then freeze the account. When a scammer tricks you into sending a tiny bit from an address that is very similar to one you’ve already paid, hoping you’ll send the wrong one the next time.
Don’t forget, blockchain payments are also chargeback-free. In most cases, once a transaction is confirmed, you can only get the money back on the condition that the person who received it decides to return it. There are some good habits that are a great help:
- Check the entire address, not just the first and last few characters.
- Transfer a small amount first before transferring a large amount to a different address.
- Avoid entering your recovery phrase in a chat window or support form, or on a website. But it’s not something that a legitimate service will ask for.
- Prior to giving any new wallet address, the crypto wallet address is scanned free of charge on our crypto wallet to check if the address is reported, which chain it is from and what the balance is.
What a Blockchain Can’t Do
We have a good opinion of this technology. Obviously. However, it has definite limitations, and ignoring that will cause people to be burned.
It cannot verify facts of the real world. A blockchain does not ensure that the information in it is accurate, it only ensures that the record hasn’t been altered since it was made. If a supplier falsifies its organic label, the chain will keep it up to date and never forget.
It is not necessarily quick and cheap. The base layer for Bitcoin supports approximately 7 transactions per second, and the fees increase accordingly when the network is busy. The majority of the normal speed is now provided by layer 2 networks that are deployed on top, such as Ethereum’s rollups and Bitcoin’s Lightning Network.
It isn’t private by default, either. Great for audits. Bad for any kind of content you don’t want an outsider reading. Irreversibility is two-sided. The same thing that prevents a fraudster from getting money back prevents you from getting money back if you type the wrong number.
We’ll test any new project with one rule: If it doesn’t have a good reason to use the blockchain over a regular database, it likely doesn’t.
The Short Version to Take With You
Remove the jargon, and a blockchain is just the following four concepts piled on top of one another: a shared record book, a mechanism for linking each page to the following one, a thousand independent copies, and a rule for consensus on what to add next. Keys determine access to the movement of what.
So, the next time a friend asks you how blockchain technology works in simple terms, instead of telling them jargon, explain the notebook! Then remind them of the part that actually protects their money. The chain will follow what they sign, so the first thing they should learn to do is to find out who they are paying before sending.
Once you’re ready for more, our plain-English crypto safety guides continue on from here.
