An Explanation of the Linux Filesystem Structure

I've been staring at the linux folder structure for some time now. I've gotten used to where everything goes, figured out that 'etc' is for configuration and 'var' is for variables and so on, but never actually seen an explanation of it. That was why I was interested to stumble upon the Filesystem Hierarchy Documenation: http://www.pathname.com/fhs/pub/fhs-2.3.html

That is a 300 page manual. Wikipedia gives a concise history, "The process of developing a standard filesystem hierarchy began in August 1993 with an effort to restructure the file and directory structure of Linux. The FSSTND (Filesystem Standard), a filesystem hierarchy standard specific to the Linux operating system, was released on 14 February 1994. Subsequent revisions were released on 9 October 1994 and 28 March 1995." and overview as well: http://en.wikipedia.org/wiki/Filesystem_Hierarchy_Standard