RuntimeIn computer science, runtime is the duration of a program's actual execution, from beginning to end. (Compare compile-time.)
The same computer programs usually run on different runtime environments.
Some programming functions can only be executed (or are more efficient or accurate) when performed at runtime: such as dynamic type checking, boundary of array checking; for this reason, some programming bugs are not discovered until the program is tested in a "live" environment, despite sophisticated compile-time checking. Languages with type checking occurring at runtime are called "dynamically typed".