06. Web2 to Web3 Day 1 Intro
Overview
Section titled “Overview”You have now seen the raw pieces — keys, blocks, transactions, contracts, gas. This lesson steps back and reframes them for someone who already builds software. If you come from Web2, most of your instincts are right about how to write code and wrong about where the trust and state live. Naming those differences up front prevents the confusion that trips up most newcomers.
Key concepts
Section titled “Key concepts”- The backend is a public, shared computer. In Web2 your server is private and you control it. Onchain, your “backend” is a smart contract whose code and data are public and run by a network you do not own. You cannot hide logic in it, and you cannot quietly patch it.
- The wallet replaces the login system. There is no username, password, or session table. Users authenticate by signing with a wallet, and the same key pair is their identity across every app. Auth is not something you build; it is something you integrate.
- State changes cost money and take time. A database write is instant and free to you; an onchain write is a transaction that costs gas and waits for a block. This changes what you put onchain versus off.
- Three roles to keep separate — the frontend (the UI you write, much like a normal web app), the wallet (holds keys, signs transactions, connects to the app), and the network / RPC (the Ethereum nodes your app reads from and broadcasts to). Later modules wire these together with providers and signers.
- No undo, no admin override. There is no support team that can reverse a transaction or reset an account. Correctness and security are front-loaded into the code, not patched in production.
Common pitfalls
Section titled “Common pitfalls”- Trying to map Ethereum onto a client-server model one-to-one. The contract is not “your server” — it is a shared, public, immutable one.
- Assuming you will build login and sessions. You integrate a wallet instead.
- Planning to store everything onchain. Because writes cost gas and are permanent and public, you store the minimum that must be trustless and keep the rest off-chain.
Check yourself
Section titled “Check yourself”- What does the wallet replace from a typical Web2 stack?
- Name the three roles — frontend, wallet, network — and what each is responsible for.
- Why can’t you treat a smart contract exactly like your private application server?
Watch the Video
Section titled “Watch the Video”
Web2 to Web3 Day 1 Intro
Video credit: Austin Griffith · Duration: 21 minutes