Criteria are often the particular requirements that someone or something must meet in order to be considered or qualify for something. An applicant for a job may be evaluated based on several criteria, including their education, experience, and references—each one of these standards is a criterion.

What is an example of a criterion?

The definition of criterion is the standard by which something is judged or assessed. An example of a criterion is the set of guidelines for a thesis which is used to determine whether your thesis was good or bad. A standard, rule, or test on which a judgment or decision can be based.

What you mean by constraints?

: something that limits or restricts someone or something. : control that limits or restricts someone's actions or behavior. See the full definition for constraint in the English Language Learners Dictionary.