In computer programming, a comment is a programming language construct used to embed programmer-readable annotations in the source code of a computer program. Those annotations are potentially significant to programmers but typically ignorable to compilers and interpreters. Comments are usually added with the purpose of making the source code easier to understand. The syntax and rules for comments vary and are usually defined in a programming language specification (see the syntax of comments in various programming languages).
Comments have a wide range of potential uses: from augmenting program code with basic descriptions, to generating external documentation. Comments are also used for integration with source code management systems and other kinds of external programming tools.
The flexibility provided by comments often allows for a wide degree of variability and potentially non-useful information inside source code. To address this, many technical commentators and software analysts subscribe to any of several "philosophies" and guidelines regarding the proper use of comments.