A compiler is a program that translates source code into object code to be understood by a specific central processing unit (CPU). The act of translating source code into object code is known as compilation. Compilation is typically used for programs that translate source code from a high-level programming language (such as C++) to a low-level programming language (such as machine code) to create an executable program. Likewise, when a low-level language is converted into a high-level language, the process is called decompilation.
A compiler is a special program that processes statements written in a particular programming language and turns them into machine language or "code" that a computer's processor uses.