How Transactions Are Sent
Transactions originate from users and are transmitted via client software to the Ethereum network. Here's how the process works:
- Client Software Role: Applications like Mist or imToken handle transaction assembly, including signature generation and compliance checks.
- Network Propagation: The client communicates with an Ethereum node to broadcast the transaction to the network for miner inclusion.
Key aspects of transactions:
- Transactions can be simple ETH transfers or smart contract calls.
- Each transaction consumes computational resources (gas) and requires payment in ETH.
- Users interact with Ethereum exclusively through transactions.
Transaction Lifecycle
- Initiation: Users sign and send one or more messages bundled as a transaction.
- Mining: Miners include the transaction in a new block.
- Confirmation: The block is added to the blockchain after network validation.
👉 Learn about gas fees and optimization
Transactions vs. Messages
Often confused, these concepts have distinct characteristics:
| Concept | Trigger | Visibility | Content |
|---|---|---|---|
| Transaction | External account | On-chain | Contains messages or contract creation |
| Message | Contract or transaction | Internal | Transfers data/value between accounts |
Message Examples:
- Function calls between contracts
- ETH transfers between accounts
Note: Smart contracts can chain messages (e.g., Contract A → Contract B → Account C), creating complex interactions invisible on-chain.
Core Characteristics of Ethereum Transactions
Atomicity
- All operations within a transaction either complete fully or revert entirely
- Guarantees state consistency even if contract execution fails
Serial Execution
- Transactions process sequentially (no parallel execution)
- EVM processes one transaction at a time per block
Non-Deterministic Ordering
Transaction inclusion order depends on:
- Network propagation speed
- Gas fees
- Miner selection criteria
- Competing blocks may contain the same transactions in different orders
👉 Understand blockchain finality
FAQ
How long does a transaction take to confirm?
Typical confirmation takes 15 seconds to several minutes, depending on network congestion and gas price.
Can transactions be canceled once sent?
Only if they haven't been mined—you can attempt replacement transactions with higher gas fees.
Why do smart contract transactions cost more?
They require additional computation (gas) for code execution compared to simple ETH transfers.
What happens if a transaction fails?
The entire operation reverts, but gas fees are still consumed for the attempted computation.
How can I speed up my transaction?
Increase the gas price to incentivize miners to prioritize your transaction.
Are transactions reversible?
No, Ethereum transactions are immutable once confirmed on the blockchain.