What is blockchain? What problems does it solve?

What is blockchain?

In the simplest terms,Blockchain is an immutable public ledger maintained by all participants。 Each transaction is packaged into "blocks" that are connected in chronological order to form a "chain" that anyone can consult but no one can tamper with.

A life-like analogy

Imagine a bookkeeping system in a village:

• The traditional way: The village chief (centralized institution) keeps the accounts alone, and everyone must trust that the village chief will not cheat. If the village chief tampered with the records, no one else would know.
• Blockchain way: Each villager (node) has a complete copy of the ledger. Each new transaction is broadcast to everyone, and everyone verifies and records it together. Anyone who tries to tamper with their ledger will be immediately identified and rejected for inconsistencies with hundreds of other copies.

Core features of blockchain

Blockchain key data

How blockchain works

To understand the working mechanism of blockchain, one needs to understand the complete process of "transaction→ broadcasting→ verification→ packaging, → on-chain".

The full lifecycle of a transaction

The internal structure of a block

// 区块数据结构（简化示意）
Block {
  header: {
    blockNumber: 19500000,           // 区块高度
    timestamp: 1710000000,           // 时间戳
    previousBlockHash: "0xabc123...",  // 前一区块哈希（链接）
    merkleRoot: "0xdef456...",        // 交易默克尔树根
    stateRoot: "0x789abc...",         // 全局状态根
    nonce: 12345,                    // PoW工作量证明（或验证者签名）
  },
  transactions: [
    { from: "0xA...", to: "0xB...", value: "1 ETH", gasUsed: 21000 },
    { from: "0xC...", to: "0xD...", value: "0.5 ETH", gasUsed: 21000 },
    // ... 数百笔交易
  ],
  receipts: [ /* 交易执行结果与事件日志 */ ]
}

Core technical principles

The security and reliability of blockchain are built on three technological pillars: cryptography, distributed systems, and game theory.

Three technical pillars

How hash links are guaranteed to be tamper-proof

// 区块链的链式结构
Block #100:  Hash = SHA256(Header100) = "0xAAA..."
  └── previousHash = "0x999..."（指向Block #99）

Block #101:  Hash = SHA256(Header101) = "0xBBB..."
  └── previousHash = "0xAAA..."（指向Block #100）

Block #102:  Hash = SHA256(Header102) = "0xCCC..."
  └── previousHash = "0xBBB..."（指向Block #101）

// 如果攻击者修改了 Block #100 中的一笔交易：
// → Block #100 的哈希从 "0xAAA..." 变为 "0xXXX..."
// → Block #101 的 previousHash 与实际不匹配 → 无效！
// → 攻击者必须重新计算 #101、#102... 所有后续区块
// → 在PoW中，这需要超过全网51%的算力 → 经济上不可行

Public Key Cryptography: Your Digital Identity

Detailed explanation of the consensus mechanism

The consensus mechanism is the rule by which all nodes in a blockchain network agree on the "content of the next block." Different consensus algorithms make different trade-offs between security, decentralization, and performance.

Comparison of mainstream consensus mechanisms

PoW vs PoS in-depth comparison

Types of blockchains

Blockchains can be divided into three main categories based on access rights and governance methods. Different scenarios require different types of blockchains.

What problems does blockchain solve?

Blockchain is not a panacea, but it solves some of the most fundamental problems in human society – problems that have plagued humanity for thousands of years.

Six core problems and blockchain solutions

The end of the crisis of confidence

"Trust issues" are the most fundamental mission of blockchain. Let's look at how blockchain can eliminate reliance on intermediaries in specific scenarios:

In the financial sector: get rid of bank intermediaries

Supply chain field: remove the information black box

• Food traceability: Every step from farm to table is recorded in the chain, and consumers can scan the code to verify the whole link information of origin, processing, and transportation
• Drug anti-counterfeiting: The production batch, logistics path, and temperature control records of each box of drugs are all on the chain to completely eliminate the circulation of counterfeit drugs
• Luxury appraisal: The brand writes the product information into the blockchain NFT when it leaves the factory, and the buyer can permanently verify the authenticity

Government affairs: remove the black box operation

• Electronic voting: The ballot is encrypted on the chain, and the counting process is open and transparent, and anyone can independently verify the accuracy of the results
• Land registration: Confirm the ownership of real estate on the chain, and eliminate double mortgages, ownership disputes and other problems
• Philanthropic transparency: Real-time tracking of donations, and the flow of every penny is open to donors

Real-world application scenarios

Blockchain technology has already generated real value in several industries, and here are the most impactful application areas:

Enterprise application data

Limitations and challenges

Blockchain is not a perfect technology. Objectively recognizing its limitations helps to use it in the right scenarios.

The main challenge at the moment

Scenarios where blockchain is not suitable

• Data that needs to be modified frequently: The immutability of blockchain is a disadvantage here
• Completely private business: Even if encrypted, on-chain transaction patterns can still be analyzed
• Latency-sensitive applications: The block time determines the minimum latency
• An internal system that does not involve multi-party collaboration: It is more efficient to use traditional databases within a single organization

Blockchain vs. traditional technology

Blockchain vs traditional databases

Blockchain vs Cloud Computing

Future development trends

Blockchain technology is in a period of rapid development, and the following trends will profoundly impact the industry landscape in the next 3-5 years:

How to get started with blockchain

Whether you want to learn about blockchain, use blockchain applications, or implement blockchain technology in your business, here are practical ways to get started.

Get started as an individual user

Enterprise landing path