A transaction is a transfer of cryptocurrency recorded on the blockchain. It includes the sender's address, the receiver's address, the amount, and a fee. The sender signs the transaction with their private key. The network verifies the signature, checks the balance, and includes the transaction in a block. Once confirmed, the transfer is final. There is no chargeback and no reversal. That finality is a feature. It is also a risk. Send to the wrong address and the funds are gone.

Transactions are not just payments. They can call smart contracts, mint tokens, vote on governance proposals, or interact with DeFi protocols. Each operation consumes gas, and complex operations cost more. A simple ETH transfer costs 21,000 gas. A Uniswap swap might cost 150,000. A transaction that runs out of gas fails and the fee is still consumed. The sender pays for the computation even if the outcome is nothing. Transaction fees are the cost of using the network. They compensate miners or validators for including the transaction in a block.

Transaction components

• Sender address — where the funds come from
• Receiver address — where the funds go
• Amount — how much is being sent
• Gas fee — payment for computation
• Signature — proof the sender authorized the transfer

A transaction is a signed message that the network agrees to include in the ledger. Everything on a blockchain is a transaction.