In UNIX® and Linux® all folders are arranged in a simple hierarchy. Starting from a top level folder (also called the root directory), the structure descends and branches containing various files and subfolders. This means that you can get from any folder to any other by going “up ” until you reach a common point then “down” through the appropriate subfolders until you reach your target.

The position of any file or folder in the structure (also called a directory tree) can be described by its “path”, which is a simple list of the folders you would have to descend through to get to the target folder or file. For example /home/pam is the subfolder pam of the subfolder home of the top level folder, and /home/pam/words.txt is the file words.txt in that subfolder. The leading “/” in these paths represents the top level folder.

Every folder accessible by your system — including those on other hard disk partitions, your floppy and CD-ROM — will appear in the tree descending from /, their exact paths will depend on how your system was set up (see also the section on Floppy and CD-ROM Drives).

Every user on a UNIX® / Linux® system has their own “home” folder to hold their personal files and settings; for example /home/john and /home/mary. The symbol ~ is often used to represent the user's home folder, so that ~/letter.txt refers to the file letter.txt in my home folder.

Note that the term “directory” is often used instead of “folder”.