How to Build Your First Web3 DApp and Master Blockchain Basics

Web 3.0 era has arrived, and this guide explains how to build your first decentralized application (dApp) from scratch.

Internet Evolution

Web 1.0 – “read‑only” web

Web 2.0 – “read‑write” web (current mainstream)

Web 3.0 – “read‑write‑yourself” web (people’s own internet)

Advantages of Web 3

Enhanced data security

Simple login using encrypted wallets

Reduced network interruptions

Registration Methods on Web 2.0 vs Web 3.0

Web 2.0:

Fill out a registration form

Check your email inbox

Verify the email

Solve captcha challenges

Web 3.0:

Connect a crypto wallet

How Web 3 Works

Web3 data is encrypted and stored across globally distributed nodes, unlike Web 2.0 where data resides on cloud or hosted servers.

Blockchain

A blockchain is a chain of blocks, each containing a list of recorded transactions. When a block fills up, it is sealed and linked to the previous block, forming the chain.

How Blockchain Operates

When a user requests a transaction (e.g., swapping cryptocurrencies), the transaction data is validated and added to a block, which is then broadcast to all nodes for verification before being permanently added to the chain.

Gas Fees

Each transaction requires a gas fee paid to nodes (miners) for validation and inclusion in the blockchain. Fees vary by network load and can increase during high demand, similar to surge pricing at gas stations. Some networks like Polygon have lower fees than Ethereum mainnet.

Smart Contracts

Smart contracts are computer programs that enable interaction with the blockchain. They can be programmed to accept payments and deliver goods, or to facilitate token swaps by automatically handling user funds.

Crypto Wallets

A crypto wallet stores digital assets (cryptocurrencies, NFTs) and is accessed via a private key – a unique alphanumeric string that must never be shared. Wallets can be browser extensions, mobile apps, or hardware devices, each having a public key that anyone can view to check transaction history without accessing the assets.

Wallet Examples

MetaMask

Coinbase Wallet

Phantom

Hot Wallet vs Cold Wallet

Hot wallets (software) are convenient but vulnerable to online attacks. Cold wallets (hardware like Ledger or Trezor) store keys offline, offering higher security; they resemble USB sticks and require purchase.

Setting Up Your First Wallet

Ensure you have a functional Chrome browser

Install the Coinbase or MetaMask Chrome extension

Follow the steps to create a new wallet

Write down the secret recovery phrase and store it securely

Note: Web 3 has no customer support hotlines; losing your private key means losing access to your assets. Always keep your wallet safe.

Pin the wallet extension to your browser toolbar for easy access

When interacting with a Web 3 site, click “Connect Wallet” in the top‑right corner

Never share your private key

Avoid clicking suspicious links in articles, DMs, or emails

Store your recovery phrase in a private, secure location

Use a hardware wallet for interacting with Web 3 sites to keep your main wallet offline