The word “blockchain” is everywhere these days, but many people struggle to explain exactly what it is. This article explains in plain language how blockchains keep records, why those records are hard to alter, and what they can—and can’t—prove.

Bitcoin was the first blockchain network to operate at scale, and $BTC is the native coin of the Bitcoin network. Current price: 81,750 (24h -2.01%).

— A ledger maintained collectively —

You can think of a blockchain as a public ledger. Unlike banks, which keep their records on their own servers, this ledger is maintained by many nodes. Every full node stores a complete copy of the records, which anyone can download and verify.

Bitcoin was the first blockchain to operate at scale. Satoshi Nakamoto published the Bitcoin white paper on October 31, 2008. On January 3, 2009, the first block (the genesis block) was mined, and it even included a headline from that day’s The Times.

— Where “blocks” and “chains” come from —

Transactions aren’t written to the ledger one by one. Instead, they’re first bundled into blocks. Bitcoin produces a block about every 10 minutes on average; after Ethereum switched to proof of stake in 2022, it began scheduling blocks in 12-second slots.

Each block records the hash of the previous block. A hash can be thought of as a “fingerprint” of a piece of data: even changing a single character produces a completely different fingerprint. Blocks are linked together end to end this way, forming a chain.

— Why it’s difficult to tamper with —

If someone tries to alter a block in the past, its hash changes, so it no longer matches the “previous hash” recorded in every subsequent block. To reconnect the ledger, they’d have to redo all the blocks that came after it.

In proof-of-work networks like Bitcoin, redoing blocks requires real computing power, and the attacker would also have to catch up with the main chain as it keeps growing across the network. The deeper a block is buried, the more expensive it is to rewrite—which is why recipients usually wait for several confirmations.

— What it can and can’t prove —

Anyone can look up transactions on a public blockchain, but addresses aren’t directly linked to real-world identities. That’s why blockchains are often described as “public and transparent, but not tied to real names.”

One more point is easy to misunderstand: being written to a blockchain only means that a record is difficult to change afterward. It doesn’t mean the information itself is true. Projects that tout “blockchain” should still be judged by where the money is going.

— A few final words —

Understanding how a blockchain keeps its ledger won’t make you money overnight, but it can help you distinguish technical facts from claims that merely borrow the concept. Only invest what you can afford, and leave yourself some room to maneuver.

If you get it, type 1. If you’re still unsure, leave a comment and keep asking.