thumb|Front panel of an [[IBM 701 computer introduced in 1952. Lights in the middle display the contents of various registers. The instruction counter is at the lower left.]]
A program counter (PC) is a register that stores where a computer program is being executed by a processor. It is also commonly called the instruction pointer (IP) in Intel x86 and Itanium microprocessors, and sometimes called the instruction address register (IAR),