StrictEvaluation is the traditional approach to evaluating expressions in a ProgrammingLanguage. It means that the values of sub-expressions are worked out before passing them to operators, and that the values of parameters are worked out before passing them to functions.

This is the norm in imperative programming used in ProgrammingLanguages like C, C++ or Java and in in "unpure" functional programming used in languages like ML and LISP. StrictEvaluation means you can predict the order that expressions will be evaluated in, so other language features like reassignable variables and a conventional I/O system become practical.

Contrast LazyEvaluation.