As a computer program executes, it loads and stores data to and from memory, as determined by instructions in the program. The instructions are themselves stored in memory, usually a different part of memory from the program’s data. Instructions are logically executed in the sequence they are stored, except that jump instructions specify a new place in the program to start executing instructions. (Some architectures use the term branch for some or all jumps, but we call them all jumps here.) Each instruction that references data memory and each jump specifies the address or addresses or the data to load or store, or of the instruction to jump to. All computers have a variety of instruction formats and address formation rules that linkers have to be able to handle as they relocate addresses in instructions.