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

Bitcoin is the earliest blockchain network to operate at scale, $BTC is the native coin of the Bitcoin network. Currently 83,769.95 (24h +0.92%).

■ A ledger maintained collectively by everyone

You can think of a blockchain as a public ledger. Unlike a bank, which keeps its records on its own servers, this ledger is maintained collectively 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 included a headline from that day’s *The Times*.

■ Where “blocks” and “chains” come from

Transactions aren’t written into the ledger one by one. Instead, they’re first bundled into blocks. Bitcoin produces a block 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” for a piece of data. Change even one character, and the fingerprint will be completely different. Blocks link together one after another, forming a chain.

■ Why it’s hard to tamper with

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

In proof-of-work networks like Bitcoin, redoing blocks takes real computing power, and the attacker also has to catch up with the main chain as it continues to grow across the network. The deeper a block is buried, the more costly 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 tied to real-world identities. That’s why blockchains are often described as “public and transparent, but not linked to real names.”

Here’s another common misconception: being recorded on a blockchain only means that the record is difficult to change afterward. It doesn’t mean the information itself is true. Projects that use the “blockchain” label still deserve scrutiny—first, find out where the money is going.

■ In summary

Understanding how blockchains keep records won’t make you money overnight, but it can help you tell technical facts apart from claims that merely borrow the concept. Knowledge may not seem useful in everyday life, but when you’re about to get burned, you’ll be glad you have it. There’s no shame in taking it slow; staying in the game matters more than how much you make on any one trade.

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