There is no such thing as a smart computer. A computer is a device that is capable of executing just a few instructions, but can do that very fast. One such instruction could be to take a value stored somewhere, and another stored somewhere else, add the two, and store the result in a third place. A program is a list of such instructions, written down in some logical and structured order, and in a human readable format. The format is called a programming language. A smart program would turn the useless device we described into a calculator.

For a lot of programming languages, a special program called a compiler exists. It translates a program from a human readable format—usually a text file referred to as source code—into a format the computer can understand, typically a binary executable file.

Your computer or tablet contains many different kinds of programs. There is a program to manage the computer, programs to manage programs, others to create programs, a program that...