Chenkaixuan's Blog

Embrace The Grind
Leave It All To God

Visitors: 993 | Views: 2395 | Analytics by Umami
0%

BlockChain

发表于 更新于

1. What is a blockchain (definition)

A blockchain is basically a special kind of database that:

  • Stores information in blocks.
  • Each block is linked (“chained”) to the one before it using cryptography.
  • Once data is written, it is almost impossible to change (immutable).
  • It is shared across many computers (nodes), not stored on just one company’s server.

So, instead of Google’s database or Facebook’s database, you have a public, decentralized ledger.

2. How it looks (visual)

1
2
3
4
5
[Block #1] --> [Block #2] --> [Block #3] --> [Block #4] --> ...
    |              |              |              |
  Data A        Data B        Data C        Data D
 (e.g. tx)     (e.g. tx)     (e.g. tx)     (e.g. tx)

  • Each block contains:
    1. A bunch of transactions / records (for example: Alice sends Bob 1 BTC).
    2. A hash (a digital fingerprint) of the previous block.
    3. A new hash for itself.

This chaining ensures:

👉 If someone tries to alter Block #2, then its hash changes, which breaks Block #3, #4, etc. → everyone sees the tampering.

3. Why is it powerful?

  • Immutable: Can’t easily change history.
  • Decentralized: No single company controls it; many nodes validate it.
  • Transparent: Anyone can verify transactions.
  • Secure: Cryptography makes it hard to fake.

4. Example (Bitcoin transaction)

Imagine Alice sends Bob 1 BTC. Here’s how blockchain handles it:

  1. Alice signs a message:

    1
    2
    "I, Alice, send 1 BTC to Bob" + digital signature

  2. This transaction goes into a block with others.

  3. Miners/validators confirm the block and link it to the chain.

  4. Now, forever, the blockchain shows:

    1
    2
    Block #257: Alice -> Bob: 1 BTC

If later Alice says “No, I didn’t send it,” it doesn’t matter — the record is permanent.

👉 So in Web3, blockchain acts like the public notebook that everyone agrees on, instead of each company having its own private notebook.

Who controls it?

  • Database (Web2):
    • Controlled by one organization.
    • Example: Facebook’s servers → only Facebook admins decide what’s stored or deleted.
  • Blockchain (Web3):
    • Controlled by everyone (decentralized).
    • Thousands of nodes store copies. If one cheats, others reject it.
1
2
3
Database:   [ Company Server ] ---> users just trust it
Blockchain: [ Many Nodes ] <--> all must agree (consensus)