|Internal documentation is written in a program as comments.
||External documentation is written in a place where people who need to use the software can read about how to use the software.
|Internal documentation would be comments and remarks made by the programmer in the form of line comments
||External documentation would be things like flow charts, UML diagrams, requirements documents, design documents etc.
|Design documents, code comments, API documentation, test plans, user stories
||User manuals, help files, installation guides, release notes
|Usually stored in internal wikis, repositories, and code documentation tools
||Can be in printed or digital format, and may include videos or interactive tutorials