The Linux kernel is explained, briefly, on our WhatIsLinux page. If you want to learn more, try these links:

• http://www.kernel.org -- The offical home page of The Linux Kernel Archives
• The Kernel-HOWTO
• http://www.linuxhq.com -- General information about the kernel
• http://www.kernelnewbies.org -- Get started hacking the Linux kernel
• http://www.kernelhacking.org -- Another "Getting Started" site
• The Linux Kernel Mailing List, or LKML
• Kernel Traffic -- Weekly summaries of the LKML
• A popular LKML archive
• LKML Frequently Asked Questions