A committed use discount is a lower price a cloud provider offers in exchange for your agreement to pay for a set amount of usage over a fixed term, commonly one or three years. The commitment is usually for a quantity, such as a number of vCPUs or an amount of memory, and you are billed for it whether or not you use all of it.
The discount can be large for steady, predictable workloads, because the provider gets certainty about future revenue. Longer terms generally give bigger discounts but reduce your flexibility.
The risk is paying for capacity you no longer need. If your usage falls, the application is retired or you move to another service, the commitment usually still has to be paid. Terms differ between providers and products, including what the commitment covers, whether it can be changed or resold and what happens at renewal. It generally does not apply to every service or to free-tier usage.
Before committing, look at your actual usage over several months, commit to the baseline you are confident will continue, and leave variable demand on standard pricing. Read the terms carefully, check whether the discount applies to the exact service and region you use, and review the commitment before it renews.