Menu

A file extension or filename extension is a suffix at the end of a filename. It is used to show the type of a computer file. This suggests what program can understand it. For example, MYWORDS.TXT is a plain text file and may be opened by a text editor. Filename extensions come after the name of the file, and many of them are three letters long.

Some examples of common file extensions are:

• HASH are hash program files
• TXT files are plain text files
• BMP are bitmap picture files
• JPG are picture files in the JPEG format
• MP3 are music files in the MP3 format
• WMA are Windows Media Audio sound files
• MPEG are motion picture encoded video files
• HTM or *HTML are Hyper Text Markup Language files such as web pages
• DOC are text documents in Microsoft Word format
• XLS are Microsoft Excel spreadsheet documents
• EXE are Microsoft Windows executable program files
• DLL are Dynamic Link Libraries, a type of executable file, in MS Windows
• ZIP are Compressed files (Lempel Ziff algorithm in an archive)
• c are C programming language source files

There are many other commonly used file extensions.