To understand blockchain, you first need to grasp its fundamental principle — essentially, it's a ledger that everyone maintains together and no one can alter.

Imagine a small town without a mayor. How did they keep records in the past? They trusted a reliable person — for example, Accountant Wang — who wrote all transactions ("Old Zhang borrowed 50 yuan from Old Li") in his small notebook. The problem is obvious: if Accountant Wang falls ill, or has malicious intent, or if the ledger is lost or tampered with, no one can clarify what actually happened.

Later, the townspeople came up with a new method: instead of trusting any single person, everyone in the town keeps the records together. Every time a transaction occurs, it is announced loudly through a loudspeaker, and everyone opens their own notebooks to copy down the transaction. What was the result?

Without a leader overseeing — no one can monopolize the bookkeeping rights. Each person's notebook is identical — no longer afraid of being controlled by one individual. Want to modify an old record? You would have to change everyone's notebooks simultaneously — which is impossible.

This logic is exactly how blockchain works. But instead of replacing "notebooks" with "blocks" in a computer, and "transactions" with digital records (like transfers, certificates, etc.).

So how does it operate specifically? Remember these three points:

**First, Decentralization**. No banks, no platforms, no intermediaries. All participating computers (we call them "nodes") are completely equal in status, working together to safeguard this ledger.

**Second, Immutability**. Each block is linked to the previous one with a "cryptographic lock" (technically called a hash algorithm). If you try to alter the contents of a block, all subsequent locks will become invalid, and the tampering will be immediately detected.

**Third, Transparency and Traceability**. All transactions are publicly recorded, anyone can verify them, and no one can alter them.