• File name consists of two parts: name and extension
• The user and the operating system can identify the type of a file using the name.
• Most operating systems allow users to specify a file name as a sequence of characters followed by a period and terminated by an extension. Example : resume.doc, threads.c etc.
• The system uses the extension to indicate the type of the file and the type of operations that can be done on that file.
• For instance, only a file with a “.corn”, “.exe”, or “.bat”, can be executed.