2. What are computer instructions

Computers are simply very efficient data processing machines.

The first ones were literally wired to carry out a specific task - such as breaking a secret code, or to carry out a scientific calculation.

If the computer was needed to do another calculation or task, then scientists and engineers would spend many days physically re-wiring the machine.

There had to be a better way.

The famous British mathematician Alan Turing wrote down the theoretical ideas behind an 'universal computing machine' that had infinite memory - Not exactly practical, but the idea of such as machine was now in place.

Then, during World War II, an American scientist named John Von Neumann working on the atomic bomb project, came up with the idea that digital data and digital instructions are essentially the same thing - it is just that digital instructions tell the computer what to do with the digital data.

So why not store both instructions and data in the same memory and simply route the instructions to the proper part of the computer? This is the idea behind the stored-program computer which is the basis of most computers in use today.

This approach allowed a computer to be re-programmed by changing the instructions rather than re-wiring it.

The instructions are called 'software'.