The error budget represents the total number of errors a particular service can accumulate over time before users become dissatisfied with the service.

Most importantly, the error budget should never equal zero. The operator’s goal should never be to entirely eliminate reliability issues, because such an approach would both be too costly and take too long – thus impacting the ability for the organization to deploy software quickly and run dynamic software at scale.

Instead, the operator should maintain an optimal balance among cost, speed, and reliability. Error budgets quantify this balance.