Runtime or execution time (program lifecycle phase)

In computer science, runtime, run time, or execution time is the final phase of a computer program’s life cycle, in which the code is being executed on the computer’s central processing unit (CPU) as machine code. In other words, “runtime” is the running phase of a program.

A runtime error is detected after or during the execution (running state) of a program, whereas a compile-time error is detected by the compiler before the program is ever executed

— Wikipedia