What is define constraint?

In computer programming and engineering, a constraint refers to a restriction or limitation that is placed on a system or a process. It is used to ensure that a system or process operates within a defined set of parameters. Constraints can be either explicit or implicit, and they are often used to optimize or improve the performance of a system. Common examples of constraints in engineering include physical limitations such as weight, size, and power consumption, or performance limitations such as speed, accuracy, or reliability. Constraints are an essential part of the design and analysis process, as they provide a framework for determining the feasibility and performance of a system or process.