Portefeuilles, clés et transactions

A wallet doesn't hold coins - it stores your private key and uses it to sign transactions. Your funds live on the blockchain, controlled by that key.

A wallet is built on an asymmetric key pair. The private key is secret and signs transactions; the public key is derived from it and safe to share.

An Ethereum address is the last 20 bytes of the hashed public key, shown as a hex string starting with 0x. It's your public on-chain identity.

Your seed phrase (12 or 24 words) deterministically generates all your keys. Anyone with it controls your funds - keep it offline and never share it.

A transaction is a signed instruction to change chain state - sending ETH or calling a contract. It carries sender, recipient, value, data, and a nonce.

The nonce is a per-account counter that climbs with every transaction. It blocks replay attacks and forces your transactions to execute in order.

The wallet signs the transaction hash with your private key. The network checks the signature against your address - proving authorization without exposing the key.

Every transaction costs gas, paid in ETH, to reward validators for the computation. You set a gas limit and fee; contract calls cost more than a plain transfer.

A transaction's lifecycle: pending in the mempool, included in a block, then confirmed as more blocks stack on top. More confirmations mean stronger finality.

After execution you get a receipt showing status (success or revert), gas used, and any emitted events. Always check the status before assuming success.

With a non-custodial wallet you hold the keys and full control. A custodial one (like an exchange) holds them for you - "not your keys, not your coins."

Recap: wallets hold keys, not coins; addresses come from public keys; transactions are signed, ordered by nonce, and cost gas; receipts confirm success and custody sets control.