Articles and tips on how to work with various operating systems, including Windows 7, Linux and FreeBSD.
Freebyte's Guide to Operating Systems, Free and Non-free
Includes: open source, commercial; Unix (BSDs, Linux); Amiga; BeOS, Zeta; RiscOS; DOS, Windows-emulators; educational; a few related topics.
How Stuff Works: Operating Systems
Unbiased enlightening tutorial with impartial description of how OSs work, and many related links.
IT - Informatics Alphabet
Describes the basic concepts of informatics, the basic principles of general purpose digital computer systems and their application in practice.
Information about Operating Systems
Operating System Documentation Project, OSDP: information on many OSs and their developers; independent objective descriptions, facts, history; in text and screenshots. [English, German, French]
Information on all types of operating systems and networking.
The OS Files
Portal for many x86 PC platform operating systems; details, news, information, secret tips, background, links, availability (current, planned); DOSs, Linux, NetWare, OS/2, Unix, Windows.
Tips and tutorials
Tips, tutorials and news about various operating systems, such as setting up Windows, Linux, iOS and programs.