What is "docstring"

In programming, a docstring is a string literal specified in source code that is used, like a comment, to document a specific segment of code. Unlike conventional source code comments, or even specifically formatted comments like Javadoc documentation, docstrings are not stripped from the source tree when it is parsed, but are retained throughout the runtime of the program. This allows the programmer to inspect these comments at run time, for instance as an interactive help system, or as metadata.

Languages that support docstrings include Python, Lisp, Elixir, Clojure, Gherkin, and Julia.