Contas e estado
EOAs e contratos
Contas e estado é uma aula grátis de Web3 & DApp Development Fundamentals no CoddyKit. Esta é a aula 4 de 4. Você pode ler a aula completa abaixo gratuitamente — depois pratica ao vivo no navegador com um editor de código integrado e um tutor de IA 24/7. Faz parte do caminho de aprendizado de Web3 & DApp Development Fundamentals, e seu progresso é sincronizado entre a web e o app CoddyKit. O curso de Web3 & DApp Development Fundamentals inclui 4 aulas no total.
Partes desta aula ainda não foram traduzidas e aparecem em inglês.
What Is the World State?
Ethereum's world state is the complete snapshot of all accounts and their data at a given moment.
Every transaction transforms this state from one valid version to the next. Accounts are the building blocks of that state.
Two Types of Accounts
Ethereum has exactly two account types:
- Externally Owned Accounts (EOAs) — controlled by private keys (users)
- Contract Accounts — controlled by their code
Both share the same 20-byte address format.
Externally Owned Accounts
An EOA is controlled by a private key. It can initiate transactions: send ETH or call contracts.
EOAs have no code of their own — they are simply key-controlled accounts that humans (or bots) operate.
EOA {
address: 0xAbc...123
balance: 4.2 ETH
nonce: 17
code: none
}Contract Accounts
A contract account holds code (bytecode) and storage. It has no private key and cannot start a transaction on its own.
It only acts when called by an EOA or another contract, running its code in response.
Contract {
address: 0xDef...456
balance: 10 ETH
code: 0x6080604052...
storage: { slot0: ..., slot1: ... }
}The Four Account Fields
Every account stores four fields:
- nonce — transaction count (EOA) or contracts created (contract)
- balance — ETH held, in wei
- storageRoot — hash of the account's storage
- codeHash — hash of the account's code
EOA vs Contract Differences
The key distinction:
- Only EOAs can initiate transactions
- Only contracts have code and significant storage
- An EOA's codeHash is empty; a contract's is not
How State Changes
State changes only through transactions. A transaction can move ETH, deploy a contract, or call a contract that updates its storage.
After each block, the world state advances to a new, agreed-upon version.
The State Trie
All accounts are stored in a giant Merkle Patricia Trie. Its root hash — the state root — is recorded in each block header.
This single hash commits to the entire world state, just as a Merkle root commits to all transactions.
block header includes:
stateRoot -> all accounts
txRoot -> all transactions
receiptRoot -> all receiptsAccount Creation
An EOA effectively exists the moment a key pair is generated — no on-chain step is needed until it transacts.
A contract account is created when a deployment transaction runs constructor code and stores the resulting bytecode.
Smart Contract Interaction
To interact with a contract, an EOA sends a transaction specifying the contract address and the function data.
The EVM looks up the contract's code by its codeHash and executes it, possibly updating storage.
Putting It Together
Ethereum's state is a collection of accounts. EOAs are key-controlled and initiate transactions; contracts hold code and storage and react to calls.
The state root in each block commits to all of it.
Quick Check
Test your accounts knowledge.
Recap: Accounts and State
You learned that:
- Ethereum has EOAs (key-controlled) and contract accounts (code-controlled)
- Only EOAs can initiate transactions
- Each account has a nonce, balance, storageRoot, and codeHash
- The state root commits to all accounts
You have completed the Web3 fundamentals track.
Perguntas Frequentes
A aula “Contas e estado” é grátis?
Sim — o texto completo de “Contas e estado” é grátis para ler aqui na web. Para praticá-la interativamente (um editor de código integrado e um tutor de IA 24/7) e desbloquear o restante do curso de Web3 & DApp Development Fundamentals, atualize para CoddyKit PRO. O curso de Web3 & DApp Development Fundamentals inclui 4 aulas no total.
O que vou aprender em “Contas e estado”?
EOAs e contratos Você pratica Web3 & DApp Development Fundamentals com código prático que executa diretamente no navegador, e um tutor de IA 24/7 responde suas dúvidas enquanto trabalha na aula.
Preciso ter experiência prévia para começar Web3 & DApp Development Fundamentals?
Nenhuma experiência prévia é necessária. Web3 & DApp Development Fundamentals no CoddyKit é estruturado para alunos iniciantes até avançados, então você pode começar aqui ou desde o início e aprender no seu ritmo. Esta é a aula 4 de 4.
Quanto tempo leva a aula “Contas e estado”?
A maioria das aulas CoddyKit leva cerca de 5–10 minutos. Cada uma é compacta e interativa, então você faz progresso constante e retoma exatamente de onde parou entre web e app.
Posso escrever e executar código nesta aula de Web3 & DApp Development Fundamentals?
Sim. Cada aula de Web3 & DApp Development Fundamentals inclui um editor de código integrado, então você escreve e executa código real direto no navegador e recebe feedback de IA instantaneamente — nenhuma configuração local necessária.