gprof is a performance analysis tool used to measure the time spent in each function of a program. It helps developers identify bottlenecks and optimize their code by providing a detailed report of function call frequencies and execution times. This information is crucial for improving the efficiency of software applications. To use gprof, developers compile their programs with specific flags that enable profiling. After running the program, gprof generates a report that can be analyzed to understand which parts of the code are consuming the most resources. This allows for targeted optimizations, leading to faster and more efficient applications.