program counter

A program counter is an integral part of a computer's Central Processing Unit. It contains a reference to the memory address of the next instruction to be fetched, ready to be executed during the next fetch-execute cycle. Immediately following an instruction fetch, the program counter is moved on to refer to the next instruction, before the current instruction is executed. The normal sequential execution of a series of instructions may be changed by executing a branch instruction, which stores a new instruction address into the program counter.