The stored-program principle, also known as the stored program concept, refers to the storage of both data and programming (i.e., instructions) within in a single, uniform memory structure known as main (or primary) memory. Main memory is the general-purpose storage area that is directly accessible by the computer's central processing unit (CPU); main memory is synonymous with "RAM," which stands for "random access memory."

Nowadays it is taken for granted that a programmer writes a computer program, which is then read into main memory for execution. However, such was not the case for the first electronic computers, which were created starting in the late 1930s until the close of the 1940s. During that period there were two competing technologies for performing advanced digital computing: relay computers and electronic computers. The terms "relay" and "electronic" referred to the kinds of devices that the computer used to...