The official website for Ubuntu Linux provides the most reliable and updated downloads. Visit ubuntu.com
Linux Mint offers a wide range of packages through their repository. Check linuxmint.org
Debian provides a vast collection of software packages. Visit debiansource.org
The GNU/Linux project maintains a large number of resources. Explore gnu.org
Cygwin allows you to run Unix-like commands on Windows. Access cygwin.com
Arch Linux has its own repositories. Check archlinux.org
Linux From Scratch is a complete guide to building Linux from scratch. Visit lfs.unixmasters.com
The Linux kernel's archives contain the latest development versions. Check kernel.org
The Linux Documentation Project provides extensive documentation. Visit doc.kernel.org
Tons of tutorials and guides are available online. Check out linuxfromscratch.org