Part of a program text included for the benefit of the reader and ignored by the compiler. Each language has its own syntax for comments, usually a form of bracketing, e.g.

Some languages, including Ada, prefer ‘end-of-line’ comments, which are introduced by a characteristic symbol and are automatically terminated at the end of a line. Older languages such as Basic and Fortran restrict comments to be whole lines and do not allow them to be appended to a line of code.