Compiling is a process of analyzing a computer program (source code) written in a programming language and converting it into a program (object code) in a form directly executable by the computer. The software for that is called a compiler. The source code is written in a language that is easy for human being to read and write, it can not be executed as a program even if it is given to a microprocessor (MPU / CPU) inside the computer as it is, a machine language program understood by the computer Must be converted. Performing this conversion collectively is called compilation and is often done at the time of software development, for example. In today's general software development, it is rare that a program that can be started by compiling alone is rarely obtained, and preprocessing (preprocessing) is necessary immediately before compiling, or in order to make a compiled program ready to be started It often goes through processes such as linking with other programs. Such a series of processes including compiling is called build or make. There are methods other than compilation for conversion to machine language, and there is a method of reading source code little by little at the time of execution and executing it concurrently while converting. It is often used in scripting languages and the like.