Extension

The last 1-6 characters of a file name are known as the file name's extension, if they are immediately preceded by a period (".").

For example, if a file is named: myfile.ext

Its filename extension is: ext

However, a file named: myfilenoext

Has no extension.

Note: File name extensions often identify the type of information stored in a file. For example. file names with an extension of "doc" usually contain documents created by Microsoft's Word and WordPad word-processing programs. Other common file name extensions are:

• exe - Executable file (a program)
• com - an older form of Executable file
• dll - Dynamic Link Library (a file containing computer instructions that are shared by two or more programs)
• bmp, gif, jpg, jpeg, png, tif, tiff, pcx, ico - Various types of image or picture files
• txt - text
• htm, html - HyperText Markup Language (a file containing the contents of a web page)