This chapter covered five methods of timing programs or functions inside of programs. The first three methods were stopwatch, date, and time. These three methods are ways to measure the total time that the program takes to execute. These methods require no modifications to the program to measure the time spent by the program. The clock and gettimeofday routines can be added to parts of a program to measure the time spent doing a section of the program. Finally, the gprof profiler and kprof can be used to profile sample programs.