Skip to content
Ethereum Applications GuildEAG Developer Course

1. Chain, Wallet & Gas

Goal

Section titled “Goal”

Understand the onchain fundamentals required before building a dApp.

Module Guide

Section titled “Module Guide”

Before you write a single line of Solidity, you need a working picture of what a blockchain actually is and what happens when you use one. That picture is the whole job of Module 1. Everything later in the course — contracts, dApps, L2s — is built on the handful of ideas introduced here, so the goal is not to memorize definitions but to be able to look at any onchain activity and explain it.

The lessons follow a deliberate path from the smallest unit outward. You start with the key pair (lesson 01): an account on Ethereum is nothing but a private key and the address derived from it, and whoever holds the key controls the account. From there the scope widens to the blockchain itself (02) — an append-only, ordered history of state — and then to the transaction (03), the single signed message that is the only way that state ever changes. Lesson 04 introduces smart contracts as accounts that hold code, so a transaction can do more than move ETH: it can run a program. Lesson 05 explains gas, the metering that makes running that program on a shared, public computer possible and priced.

The second half reframes all of this for a working developer. The two Web2 to Web3 sessions (06–07) contrast the mental model you already have — servers, databases, password resets — with the onchain one, where there is no reset and the wallet is the user’s identity and signing device. The module closes with EVM fundamentals (08), which ties the pieces together: the EVM is the shared virtual machine that executes every contract and updates the one global state that all those blocks record.

Read each lesson page even if you watch the video — the written notes restate the core ideas, flag the mistakes people actually make (leaked keys, confusing gas limit with fee), and give you a few self-check questions. By the end you should be able to configure a testnet wallet, send a transaction, and open a block explorer and narrate exactly what you are looking at. That fluency is the prerequisite for Module 2, where you begin writing the contract code that these transactions call.

Topics

Section titled “Topics”
  • Ethereum and L2 fundamentals
  • Wallets, private keys, seed phrases, and addresses
  • Transaction fields, nonce, Gas, and confirmations
  • RPC, block explorers, and testnet ETH
  • Accounts, EOAs, and contract accounts

Assigned Lessons

Section titled “Assigned Lessons”

Each lesson has its own page with the embedded video, focus points, and notes.

Open the Module 1 lesson sequence

Lab Tasks

Section titled “Lab Tasks”

Open Lab 1: Inspect Ethereum from the CLI

  • Configure a testnet wallet
  • Obtain testnet ETH
  • Use CLI or RPC to query block number, balance, and transaction data
  • Explain a transaction in a block explorer

Learning Outcomes

Section titled “Learning Outcomes”

You will be able to

  • Explain the roles of addresses, transaction fields, Gas, and nonce
  • Configure a testnet and complete a test transaction
  • Query block height and account balance with CLI or RPC
  • Use a block explorer to explain what happened in a transaction