Block by Block: a field guide to Web3

Field guide · 2026 edition ✦ Beginner friendly

Beyond Today's Internet, Welcome to Web3

Most of the internet today is built around platforms owned and controlled by companies. Web3 explores a different approach introducing ideas like blockchain, digital ownership and decentralised apps.

Start from the beginning ✦ Take the quiz
  • 7 short chapters
  • 10 key terms decoded
  • 5 question quiz
The idea of blockchain was introduced with Bitcoin, the first version of a digital currency
2009
Years since Bitcoin launched, and Web3 is still growing
~10+
The total value of the crypto market, and counting
$12T+
Of people around the world already use Web3 apps and platforms
Millions
Live diagram From today's internet to Web3 Top: today's internet, where four users all send their data into one company-owned platform. Bottom: Web3, where a decentralised app, your wallet and a token you own all connect to a shared chain of blocks copied across many computers. Golden sparkles travel along the Web3 connections. TODAY · PLATFORMS you friend seller creator Company owns the data & rules WEB3 ↓ WEB3 · SHARED & OWNED dApp Your wallet Token you own BLOCK #1 BLOCK #2 BLOCK #3 one shared ledger · copied on thousands of computers · no single owner
✦ You own it No middleman Copied 1000s of times
Scroll to explore

01 · The shift

So, who holds the database?

who-holds-the-database.app

Read · Write · Own

Data is not stored on single corporate servers (like Google, Amazon, or Meta). Instead, it's distributed across peer-to-peer computer networks using blockchain technology. Users genuinely own their digital assets, identities, and content via tokens, Non-Fungible Tokens (NFTs), and cryptocurrencies, rather than just leasing access from a platform.

Transactions and data sharing happen directly between users via smart contracts (automated digital agreements) without needing a middleman like a bank or credit card company. Anyone can participate without approval.

Users are now Owners.

Reality check. Web3 does not replace Web2. Almost every real product is a hybrid. The interface you are looking at is ordinary HTML served from an ordinary web host. Only the part that has to be ownable and verifiable is worth the cost of putting on a chain.

02 · The secret sauce

Hashes, keys & signatures

Three pieces of maths quietly power every Web3 app. A hash fingerprints data, a key pair proves who you are, and a signature lets you approve things without ever revealing your secret. Play with each one below.

Explain it
01

The fingerprint machine

SHA-256

SHA-256 is a cryptographic hash function: a one-way blender for data. Pour in anything, a single word or an entire book, and it always gives back a fingerprint of exactly the same size: 256 bits, written as 64 characters.

  • Same input, same hash. Every time, on every computer.
  • Any size in, 256 bits out. A letter or a library, same length.
  • Tiny change, totally new hash. This is called the avalanche effect.
  • No going back. You can’t work out the input from the hash.

In blockchains, every block stores the hash of the block before it. Change one old transaction and its hash changes, breaking every link after it.

sha256 playgroundlive

Hash (64 hex characters = 256 bits)

02

Your identity, in three steps

Cryptographic keys

Your Web3 identity starts with a huge random number: your private key. From it, maths creates a public key, and from that, a short wallet address you can share. Each arrow only works one way, so nobody can travel backwards from your address to your secret.

Secret · never share

Private key

A random number with 78 digits. Guessing it is harder than picking one atom out of the universe.

Public

Public key

Used by others to check your signatures.

Share freely

Wallet address

Your account number. People send tokens and NFTs here.

Demo only: values are made in your browser for learning and never used for real funds.

03

Approve without revealing

Digital signatures

When you send a transaction, your wallet uses your private key to create a signature: a unique stamp made from both your key and the exact message. Anyone can check the stamp with your public key and know it was you, but the stamp never reveals the key itself.

  1. 1
    Write the transaction.
  2. 2
    Sign it inside your wallet with the private key.
  3. 3
    Broadcast the message + signature. The key stays home.
  4. 4
    Verify: every node checks it with your public key.
signature lablive
Private keystays in wallet

Signature

Not signed yet

Public keyanyone can use

Sign the message, then verify it.

Why it matters in Web3

Ownership

Whoever holds the private key controls the address and everything in it. No bank account, no company login: the key is the ownership.

private key → address → your assets

Authentication

Signatures replace passwords. Apps check a signature against your public key to know it’s really you, and your secret never leaves your wallet.

sign → verify → access granted

Integrity

Hashes lock every transaction and block in place. Change a single character anywhere and the fingerprints stop matching, so everyone can spot it.

data → hash → chain of blocks

The golden rule: lose your private key and nobody can recover it; share it and anyone can take everything. That is why wallets hide it behind a seed phrase, and why no real app will ever ask you for it.

03 · The vocabulary

The Big 6

Every Web3 headline is mainly based on these 6 topics. Once you understand what they mean, the whole concept becomes easy and readable.

04 · The big picture

What actually happens in Web3

Follow one action from your click to the blockchain. Every Web3 app, whether it moves money, NFTs or votes, runs on this same loop.

The one-line difference

Web2 · today
YouCompany serverTheir database

They approve it. They own the record.

Web3
YouNetwork of nodesBlockchain

The network approves it. You own the record.

Follow one transaction

  1. You · start hereStep 1

    You tap “Send”

    You want to do something online that involves value or a decision.

    Pay a friendBuy an NFTCast a vote
  2. Your walletStep 2

    Your wallet signs it

    Your private key adds a digital signature: proof that you, and only you, approved this action.

    send 10 tokens → 0x9f…c21✓ signed 0x3a7…e1b
  3. The networkStep 3

    It’s broadcast to the network

    The signed request goes out to thousands of independent computers called nodes. No company sits in the middle.

  4. Every node checksStep 4

    Is it valid?

    • Is the signature real?
    • Is there enough balance?
    • Does it follow the rules?
    No
    Rejected. Nothing changes, and nobody’s balance moves.
  5. The codeStep 5

    A smart contract runs the rules

    If an app is involved, its smart contract applies the rules automatically: swap the token, transfer the NFT, count the vote.

    if (conditions met)  execute();
  6. ValidatorsStep 6

    The network agrees

    Validators reach consensus on the order of transactions and pack them into a new block, using Proof of Stake or Proof of Work.

  7. The blockchainStep 7

    The block is chained forever

    The new block links to the one before it. Every node stores the same copy: public, permanent and extremely hard to tamper with.

  8. You · finishStep 8

    Done. You own the result.

    The tokens, the NFT or your vote now sit at your address. Anyone can verify it, and no one can quietly undo it. It usually takes seconds to minutes.

    Tokens receivedNFT at your addressVote on record

Why it matters

No middleman

The network, not a company, decides what happens.

You hold the keys

Your private key is your identity and your money. No one can reset it for you.

Code is the rulebook

Smart contracts run the same way for everyone, automatically.

Public & permanent

Every step is recorded where anyone can check it, forever.

05 · Test yourself

Myth or fact? Quiz time

Five quick questions on the things people most often get wrong about Web3. Pick an answer and see the real story behind each one. No sign-up, nothing saved.

06 · Try it

Say hello with a wallet

A "log in" with no email, no password and no account. Your browser wallet proves you control an address, and this page reads back what the chain already says about it. Nothing is sent anywhere: every value below comes straight from your wallet's own node connection.

Connection Not connected

0x000…0000

Your public address, safe to share. It is derived from your public key.

Network
…
Chain ID
…
Balance
…
Recent activitySample data
  • ↓Received from 0x3b1…a07+0.2500 ETH
  • ↑Sent to 0x9f4…c21−0.0800 ETH
  • ◆Minted NFT #0020.0150 ETH
  • ✓Voted on Proposal #12gas only
Copied

What just happened

  • No password was created. The page asked your wallet for permission; the wallet returned the address it is willing to reveal. That is the entire handshake.
  • Your key never moved. Private keys never leave the wallet. Websites can only ever ask it to sign something, and you approve or reject each request.
  • Connecting costs nothing. Reading the chain is free and takes no gas. Only transactions that change state are paid for.
  • No legitimate site will ever ask for your seed phrase. Not for support, not to "verify", not to "sync". Anyone who asks is stealing from you. This page never will: it has no field to type one into.
  • Read what you sign. A signature request that grants unlimited spending approval looks almost identical to a harmless one. If a prompt is confusing, reject it. Rejecting is always free.

No wallet installed? The demo is entirely optional. Everything else on this page works without one. If you want to try it, install MetaMask and consider pointing it at a testnet such as Sepolia, where the money is fake.

07 · Decoder

Crack the code words

Ten terms you will see in every thread, every whitepaper and every scam. Pick one to decode it in plain English, with a picture.

SENDER 0x7a3F…9c2E your address anyone can send to it · only you can spend from it
Basics 1 / 10

Address

In plain words

Your public account number on the blockchain. Share it freely so people can send you tokens or NFTs.

Example

0x7a3F9c2E…b41D9c2E