A 3‑Step Guide to Understanding Blockchain Technology

Since the new year, many readers have asked "What is blockchain?" This translation of an English blog, based on Dr. Xiao Feng’s recent talk, uses plain language to explain blockchain in three steps: the blockchain ledger, the peer‑to‑peer network, and the consensus mechanism.

Step 1: Understanding the Blockchain Itself

At its simplest, a blockchain is a way of structuring data as an ever‑growing ledger, similar to a book that never ends. Each block contains data and a timestamp that functions like a page number, linking blocks together in a chain. Cryptography ensures any change to a block is immediately detectable, making the ledger trustworthy for recording valuable records such as Bitcoin transactions.

Step 2: Understanding the Role of the Peer‑to‑Peer Network

If the ledger were stored on a single computer, its shutdown would render the system unusable. Instead, the blockchain is distributed across many computers (nodes) worldwide. Each node stores a full copy of the chain and updates it whenever a new block is added, providing advantages such as continuous access, decentralised verification, resistance to attacks, and immutability.

These nodes work together in a peer‑to‑peer network, offering benefits like:

Ability to check transaction status anytime, anywhere.

No reliance on a single party for the latest state.

Resistance to attacks that would need to compromise thousands of computers simultaneously.

Prevention of data deletion or tampering without altering every copy.

However, the network alone cannot guarantee correctness; consensus mechanisms resolve disputes about which version of the ledger is valid.

Step 3: Understanding Consensus Mechanisms

Consensus allows all nodes to agree on the state of the ledger without trusting each other. It consists of simple rules that dictate how blocks are added, when a block is considered valid, and how conflicts are resolved.

Common mechanisms include:

Proof of Work (PoW) : Miners solve computational puzzles; the first to solve adds a block roughly every ten minutes and receives a reward.

Proof of Stake (PoS) : Validators are chosen based on the amount and age of their holdings.

When a block is proposed, all nodes verify its validity—checking signatures, transaction correctness, and adherence to protocol rules. Invalid blocks are rejected.

In case two miners add conflicting blocks simultaneously, a "fork" occurs. The network resolves this by adopting the longest chain, as miners naturally gravitate toward the chain with the most cumulative work, causing the shorter fork to disappear (soft fork) or, in rare cases, persist as a hard fork.

The combination of a tamper‑evident ledger, a decentralized network, and robust consensus makes blockchain highly secure; attacking it would require more computational power than the entire honest network combined.

Source: https://mp.weixin.qq.com/s/nzatQ1HkwHRfaFgrPdNgMA