Gas Limit

The maximum amount of units of gas userscan spend on a transaction on Ethereum blockchain. The limit is dictated by the protocol but can be changed with consensus from the community. It has been raised several times over the course of Ethereum's history due to network congestion but there are limits to how high it can be raised before it causes chain bloat and makes running a full node too burdensome for the average person, leading to node centralizaiton.