The gas limit is the maximum amount of gas a user is willing to spend on a transaction or smart contract execution on the Ethereum blockchain. Setting the gas limit too low may cause a transaction to fail, while setting it too high results in unused gas being refunded.
Example
“The user set a gas limit of 21,000 for a simple ETH transfer, which was sufficient, but a complex smart contract interaction required a gas limit of 200,000 to execute successfully.”