Gas limit is a fundamental concept in working with Ethereum and other similar blockchain networks. It defines the maximum amount of computational work (measured in gas) that can be consumed by a transaction or contract execution. Each operation in Ethereum requires a certain amount of gas, which is used to measure how much computational power it will need. By setting a gas limit, a user prevents their transaction from using an excessive amount of resources, which can help maintain network efficiency and avoid unintended high costs.