what is a compiler?

[WrigleyF]

I've heard a lot about computer programs called compilers, but I'm not exactly clear on what they do.

[suwunk]

A compiler is a computer program (or set of programs) that transforms source code written in a programming language (the source language) into another computer language (the target language, often having a binary form known as object code). The most common reason for wanting to transform source code is to create an executable program.

Compiler - Wikipedia, the free encyclopedia