Individual files are grouped into file folders called directories. Directories may contain files or sub-directories. This is shown below The structure of the UNIX file system however, has some general rules that you can use to navigate through it. Specifically, it defines a set of generic directories that hold a predictable set of files. Each system administrator may add to or delete from these standard directories, but it is a good bet that you will see the following hierarchy on freshly installed UNIX systems.
Lets take a look at a few of the more important ones from the perspective of a web technician.
This directory contains binary files and executables that are considered basic to the use of the system. For the most part, you do not need to access this directory yourself. However, it is a good idea that you know where it is located. We will talk more about permissions later. This directory contains libraries for any installed compilers.