What is a program?
A program is a sequence of instructions that specifies how to perform a computation. The computation might be something mathematical, such as solving a system of equations or finding the roots of a polynomial, but it can also be a symbolic computation, such as searching and replacing text in a document or (strangely enough) compiling a program.
There are few basic instructions appear in every programming language:
input: Get data from the keyboard, a file, or some other device.
output: Display data on the screen or send data to a file or other device.
math: Perform basic mathematical operations like addition and multi lication.
conditional execution: Check for certain conditions and x cute the a ro riate code.
repetition: Perform some action repeatedly, usually with some variation.