M.Tim Jones an embedded software engineer and the author of several books has written a short but very informative article explaining the anatomy of the GNU/Linux kernel. He starts with a short history of Linux and moves on to giving a brief introduction of Linux kernel and its properties.
Then we get to know the major sub systems of Linux kernel such as the System call interface, Process Management, Virtual File System (VFS), Memory management, Network stack, Architecture and device drivers. Finally there is a short synopsis of the interesting features of Linux kernel.
I found it a very nice read especially with the accompanying images which makes it quite easy to visualize what is explained. After all don't they all say - a picture is worth a 1000 words ?
Read the article on the Anatomy of the Linux kernel at IBM Developerworks to know a little about the working of Linux.