" Two days later, there was Pooh, sitting on his branch, dangling his legs, and there, beside him, were four pots of honey..." (A.A. Milne)
This chapter describes the important parts of a standard Linux directory tree, based on the Filesystem Hierarchy Standard . It outlines the normal way of breaking the directory tree into separate filesystems with different purposes and gives the motivation behind this particular split. Not all Linux distributions follow this standard slavishly, but it is generic enough to give you an overview.