Deciphr Academy
Track 1 · Foundations · Module 4

Ethereum and smart contracts

A shared computer that runs programs nobody can quietly change.

Lessons
6
Reading
37 min
Quiz
15 questions
Pass mark
80%
  1. 1A shared world computerWhat is Ethereum?5 min
  2. 2Accounts: people and contractsWhat are the two types of Ethereum account?6 min
  3. 3What a smart contract isWhat is a smart contract?7 min
  4. 4The EVMWhat is the Ethereum Virtual Machine (EVM)?6 min
  5. 5The Merge: from mining to stakingWhat was the Ethereum Merge?6 min
  6. 6Reading a simple contractHow do you read a simple Solidity smart contract?7 min

The case used in this module

Each module tells its own made-up Brindlecove story, so details can differ from one module to the next.

Key words

Ethereum Virtual Machine (EVM)
The one shared computer that every Ethereum node keeps a copy of and agrees on. It runs smart contracts.12
Smart contract
A program that runs on Ethereum: code and data stored at its own address.3
Externally-owned account (EOA)
An Ethereum account controlled by whoever holds its private keys. It can start transactions.4
Contract account
An Ethereum account controlled by its smart contract code. It has no private key.4
Wei
The smallest unit of ETH. There are 1,000,000,000,000,000,000 wei (a 1 followed by 18 zeros) in 1 ETH.54
Gas
The unit that measures how much computing work an action on Ethereum needs.5
Bytecode
Low-level machine instructions. Smart contract code is compiled into bytecode so the EVM can run it.6
Timelock
A forced delay before an approved change to a system takes effect, giving users time to leave if they disagree.7
Proof-of-stake
The way Ethereum has agreed on new blocks since 2022: validators lock up ETH that can be destroyed if they cheat.89
Validator
A participant who has staked ETH to check new blocks and sometimes propose them.8
The Merge
The upgrade of 15 September 2022 that joined Ethereum with the Beacon Chain and replaced mining with staking.10
Solidity
A high-level language for writing smart contracts that run on the EVM.11
Sources
  1. Intro to Ethereum. ethereum.org developer docs, page updated 22 April 2026.
  2. Ethereum Virtual Machine (EVM). ethereum.org developer docs, page updated 26 July 2026.
  3. Introduction to smart contracts. ethereum.org developer docs, page updated 25 February 2026.
  4. Ethereum accounts. ethereum.org developer docs, page updated 6 August 2026.
  5. Gas and fees. ethereum.org developer docs, page updated 24 June 2026.
  6. Verifying smart contracts. ethereum.org developer docs, page updated 22 October 2025.
  7. Upgrading smart contracts. ethereum.org developer docs, page updated 21 October 2025.
  8. Proof-of-stake (PoS). ethereum.org developer docs, page updated 7 October 2026.
  9. Proof-of-work (PoW). ethereum.org developer docs, page updated 13 April 2026.
  10. The Merge. ethereum.org roadmap, page updated 15 May 2026.
  11. Solidity documentation (home page). Solidity documentation, The Solidity Authors.