A program is a specification of a computation. Often, a program is expressed in a programming language just so that it can be executed on a computer. It must be implementable on a computer. It must be capable of acceptably efficient implementation. Computers are exceptionally complex machines, and using and programming them is exceptionally complex.
Programmers are pioneers and researchers.
These are based on mathematical expressions. Introduced subroutines, separate compilation. Introduced data structuring, and file handling was built into the language. Attempt to minimise the importance of programmers. Classes, data abstraction, object-oriented .