We see the word “blockchain” almost every day, 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.

Corresponding cryptocurrency: $BTC Current price: 78,107.48 (24h +0.6%).

📌 A ledger maintained by everyone together

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 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).

📌 How did “blocks” and “chains” come about?

Transactions aren’t written into the ledger one at a time. Instead, they’re first bundled into blocks. Bitcoin produces a block on average every 10 minutes. Since switching to proof of stake in 2022, Ethereum has scheduled blocks in 12-second slots.

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

📌 Why is it so hard to tamper with?

If someone tries to alter a block in the past, its hash will change, and the “previous hash” recorded in every block after it will no longer match. To reconnect the ledger, they would 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 higher the cost of rewriting it. That’s 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 thing that’s easy to misunderstand: being recorded on a blockchain only means that the record will be difficult to change afterward. It doesn’t mean the contents of the record are true. Projects that use “blockchain” as a selling point still need to be scrutinized for where the money goes.

📌 In summary

Understanding how a blockchain keeps records won’t make you money right away, but it can help you distinguish between technical facts and claims that merely borrow the concept. Learn the principles before getting involved, and don’t make decisions based on gut feelings.

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