Python Documentation is the official reference site of the Python Software Foundation, with the language tutorial, library reference and guides for every Python version.
ArchWiki is the community-maintained documentation wiki for Arch Linux, widely praised for its detailed guides on installation, configuration and troubleshooting Linux systems.
Martin Fowler is the personal site of software author Martin Fowler, with articles on software architecture, refactoring, agile and design patterns, popular with engineers.