Definition
The maximum amount of gas (computational units) a user is willing to spend on a transaction. Setting it too low causes the transaction to fail (and you still pay the gas used). Setting it too high uses more ETH if all gas is consumed.
Why It Matters
Understanding gas limits prevents failed transactions that still cost money. Most wallets like MetaMask estimate gas limits automatically, but knowing the concept helps troubleshoot issues.
Example
A simple ETH transfer uses about 21,000 gas. A complex DeFi interaction might need 200,000+ gas. If you set a limit of 21,000 for a DeFi transaction, it will fail.
Related Terms
Gas Fee
Ethereum
Transaction
Mempool