Web3

Date: 27.07.2025 web3

What is Web3?

Web3 (or Web 3.0) refers to the next generation of the internet that emphasizes decentralization, blockchain technology, and user ownership of data. Unlike Web2 — where centralized platforms like Google, Facebook, or Amazon control data and services — Web3 aims to shift power and control back to users through open, trustless, and permissionless systems.

Key Characteristics of Web3

Decentralization: Instead of being hosted on centralized servers, Web3 apps run on blockchains or peer-to-peer networks.
Ownership: Users truly own their digital assets via NFTs, crypto wallets, and smart contracts.
Self-sovereign identity: Login is often through crypto wallets (e.g., MetaMask) rather than traditional email/password accounts.
Open-source and composability: Many protocols and apps are open, enabling developers to build on top of each other’s work.
User participation: Governance is often community-led via DAOs (Decentralized Autonomous Organizations).

Example of Web3 Applications

Instead of Facebook owning and monetizing your personal data (as in Web2), in Web3 you could control access to your data and even earn tokens when others use it — through cryptographic and economic mechanisms.

What is an NFT?

NFT stands for Non-Fungible Token. It is a unique digital asset stored on a blockchain, representing ownership of something distinct — such as artwork, music, videos, virtual real estate, or even game items.

Key Concepts of NFTs

Non-fungible: Unlike cryptocurrencies like Bitcoin or Ethereum (which are fungible, meaning one can be exchanged for another), NFTs are unique and cannot be swapped 1:1.
Token: A digital certificate of ownership stored on a blockchain (usually Ethereum).
Provenance & Ownership: NFTs let you prove the originality and ownership history of a digital item — everything is recorded on-chain.

Example of an NFT, an NFT might represent:

A digital painting from an artist
A music track or album
A video clip or meme
An item or skin in a Web3 game
A domain name (like .eth)
Access to a private community or event

Why It Matters, NFTs enable

Creators to monetize digital content directly
Collectors to own, trade, and showcase digital assets
Gamers to truly own in-game items and transfer them between platforms
Developers to create economies in decentralized applications

What is MetaMask?

MetaMask is a cryptocurrency wallet and browser extension (also available as a mobile app) that allows users to:

Store and manage their cryptocurrencies (like ETH),
Interact with decentralized applications (dApps) on the blockchain (mainly Ethereum and compatible chains),
Securely sign blockchain transactions and smart contracts.

MetaMask key features

Wallet: Stores Ethereum and other ERC-20/ERC-721 tokens.
dApp Browser: Lets you connect and interact with Web3 apps directly (e.g., NFT marketplaces, DeFi platforms, games).
Private Keys: MetaMask gives you full control — your keys are stored locally (not on a server).
Network Switching: Easily switch between Ethereum Mainnet, testnets (like Goerli), and other chains (like Polygon, BNB Chain, Avalanche).
Seed Phrase: When creating a wallet, MetaMask provides a secret recovery phrase (12–24 words) used to restore your wallet if needed.

Example Use Case

You visit an NFT marketplace like OpenSea.
You connect your MetaMask wallet to the site.
You browse NFTs, select one, and sign the transaction using MetaMask.
The NFT is sent to your wallet — all without a centralized service.

What is Solidity?

Solidity is a programming language specifically designed for writing smart contracts that run on the Ethereum Virtual Machine (EVM) — the core of the Ethereum blockchain.

Key Facts:

High-level: Similar to JavaScript, Python, and C++ in syntax, making it easier to learn.
Statically typed: Variables have fixed types, making it more predictable and secure.
Compiled: Solidity code is compiled into bytecode that runs on the blockchain (EVM).
Smart Contracts: Solidity is used to create self-executing contracts — programs that automatically enforce rules, such as NFT ownership, token transfers, DAOs, DeFi protocols, and more.


// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

contract HelloWorld {
    string public message;

    constructor(string memory _message) {
        message = _message;
    }

    function updateMessage(string memory _newMessage) public {
        message = _newMessage;
    }
}

This contract stores a message on the blockchain.
Anyone can call updateMessage() to change it.

Where It’s Used:

Ethereum
Polygon
BNB Smart Chain
Arbitrum, Optimism, and other EVM-compatible chains

Why Solidity Matters in Web3:

It enables trustless, decentralized applications.
Developers can build everything from NFTs, DeFi protocols, DAOs, to games — all running autonomously on-chain.

What are Smart Contracts?

Smart contracts are self-executing programs stored on a blockchainthat automatically carry out actions when certain conditions are met— without needing intermediaries like banks, lawyers, or centralized servers.

They are a core part of Web3, enabling decentralized applications (dApps) like NFT marketplaces, DeFi platforms, and blockchain games.

Key Characteristics

Autonomous: Once deployed, they run exactly as written and can't be changed (immutable).
Transparent: Anyone can read the contract's code and verify what it does.
Deterministic: Same input always produces the same output — no surprises.
Trustless: They remove the need to trust a third party — just trust the code.

A simple smart contract for an NFT sale might:

Check if the buyer sends enough ETH.
Transfer the NFT to the buyer.
Send ETH to the seller.

All this happens automatically — no need for an auction house or payment processor.

Smart contracts run on blockchains that support them — like:

Ethereum (most common)
Solana
BNB Smart Chain
Polygon
Avalanche
Near, Arbitrum, and more

They are usually written in languages like Solidity (for Ethereum) or Rust (for Solana).

Use Cases:

DeFi: Loans, swaps, yield farming (e.g., Uniswap, Aave)
NFTs: Minting, trading, royalties
DAOs: Governance and voting mechanisms
Games: In-game items and ownership
Escrow: Automatic fund release when conditions are met