A subprogram describes the interface to and the actions of the subprogram abstraction. It is a program inside any larger program that can be reused many times. A Subprogram is implemented using the call and return instructions in Assembly Language. The call instruction is present in the main program and the return instruction is present in the subprogram itself. Unlike in the sequence program, the Main Program is put on hold when a subprogram is performed. Furthermore, on the successful running of the subprogram, main program starts from the next sequential address in the program counter (GeeksforGeeks, 2022).