Filename

A filename (also written as two words, file name) is a name used to uniquely identify a computer file stored in a file system. Different file systems impose different restrictions on filename lengths and the allowed characters within filenames.

A filename may include one or more of these components:

• host (or node or server) – network device that contains the file
• device (or drive) – hardware device or drive
• directory (or path) – directory tree (e.g., /usr/bin, \TEMP, etc.)
• file – base name of the file
• type (format or extension) – indicates the content type of the file (e.g., .txt, .exe, .COM, etc.)
• version – revision or generation number of the file

The components required to identify a file varies across operating systems, as does the syntax and format for a valid filename.