Von Neumann Architecture

Von Neumann architecture is a design for a computer in which a program's instructions and the data those instructions work on are held together in the same main memory. This idea is called the stored program concept.

When a program runs, its instructions are loaded into main memory, and the data it is using is kept there too. For example, a quiz program's instructions sit in the same memory as the player's current score and the text of each question. There is no separate memory just for instructions: when the CPU needs an instruction or a data value, it fetches it from this one shared main memory.

Because instructions and data share one main memory, a computer does not need its circuits changing to run a different job. You can close a photo editor, load a music player, and the same hardware will run the new program. The change is in what is stored in main memory, not in the hardware itself.