Minification (also minimisation or minimization) is the process of removing all unnecessary characters from the source code of interpreted programming languages or markup languages without changing its functionality. These unnecessary characters usually include white space characters, new line characters, comments, and sometimes block delimiters, which are used to add readability to the code but are not required for it to execute. Minification reduces the size of the source code, making its transmission over a network (e.g. the Internet) more efficient. In programmer culture, aiming at extremely minified source code is the purpose of recreational code golf competitions.
Minification can be distinguished from the more general concept of data compression in that the minified source can be interpreted immediately without the need for a decompression step: the same interpreter can work with both the original as well as with the minified source.
The goals of minification are not the same as the goals of obfuscation; the former is often intended to be reversed using a pretty-printer[citation needed] or unminifier. However, to achieve its goals, minification sometimes uses techniques also used by obfuscation; for example, shortening variable names and refactoring the source code. When minification uses such techniques, the pretty-printer or unminifier can only fully reverse the minification process if it is supplied details of the transformations done by such techniques. If not supplied those details, the reversed source code will contain different variable names and control flow, even though it will have the same functionality as the original source code.