Web3 basics

What is Web3?

Web3 represents the next evolution of the internet — a decentralized network where users control their own data, identity, and assets. Unlike Web2, where centralized companies control the infrastructure, Web3 is built on blockchain technology that enables trustless peer-to-peer interactions.

Key principles of Web3:

• Decentralization — No single entity controls the network.
• Ownership — Users own their data and digital assets.
• Trustless — Interactions don't require trusted intermediaries.
• Permissionless — Anyone can participate without approval.

Blockchain fundamentals

A blockchain is a distributed, immutable ledger that records transactions across a network of nodes. Each block contains a set of transactions, and once added to the chain, it cannot be altered without consensus from the network.

Block #1 (Genesis)
├── Timestamp: 2024-01-01T00:00:00Z
├── Transactions: [...]
├── Previous Hash: 0x0000...0000
└── Hash: 0xabc1...def2

Block #2
├── Timestamp: 2024-01-01T00:10:00Z
├── Transactions: [...]
├── Previous Hash: 0xabc1...def2
└── Hash: 0x1234...5678

Wallets and identity

In Web3, your wallet is your identity. It consists of a cryptographic key pair: a public key (your address) and a private key (your secret). You use the private key to sign transactions, proving ownership without revealing the key itself.

// Your private key generates your public key
const privateKey = "0x..."; // Keep this secret!
const publicKey = derivePublicKey(privateKey);

// Your address is derived from the public key
const address = deriveAddress(publicKey);
// → "0x742d35Cc6634C0532925a3b844Bc9e7595f..."

// You sign messages to prove ownership
const signature = sign(message, privateKey);
const isValid = verify(message, signature, address);
// → true

Smart contracts

Smart contracts are self-executing programs deployed on the blockchain. They run exactly as programmed without downtime, censorship, or third-party interference. CinaCoin supports smart contracts across multiple chains.

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.19;

contract SimpleStorage {
    uint256 private value;

    function set(uint256 _value) public {
        value = _value;
    }

    function get() public view returns (uint256) {
        return value;
    }
}