Programming language

Layman (level 1)

A set of particular words and rules created by some person or a group of people. With the help of a special computer programs, such text (called "code" or "program") can be converted into a series of instructions for a computer.

Beginner (level 2)

A formal language, which comprises a set of instructions that produce various kinds of output. Programming languages are used in computer programming to implement algorithms. (source: wikipedia).

Expert (level 3)

A notation for writing programs, which are specifications of a computation or algorithm. Often, a language is considered to be a true programming language only if it's Turing-complete.