File Extensions - What Do They Mean?

File extensions are the letters at the end of a digital file name identifying the type of file. The file extension lets you know which software or software type was used to create the file and the software or plug-in required to view or play the file.

Some file formats (identified by the file extension) require a plug-in to play or view the file.

What is a plug-in? A plug-in is a small piece of software that expands the capabilities of your computer to play or display different file formats. Your computer requires a plug-in to play audio and video file and to view pictures and graphic files.

.gif – the most common graphics file format on the Internet; stands for Graphics Interchange Format; it is commonly used for clipart files

.jpg/.jpeg – common file format for photographs rather than clipart and other graphics

.bmp – stands for bitmap; the largest graphic file format; these files can be re-sized without affecting the quality of the graphic

.tiff – high quality, high resolution graphics file format

.mp3 – common sound file format found on the Internet; your computer would need a an mp3 player/plug-in installed to play these file types

.au – most common sound file format found on the Internet

.ra – Real Audio file; a Real Audio plug-in is required to play these files

.avi – requires Windows Media Player plug-in to display these files

.mov/.movie – requires QuickTime plug-in to display these files

.rm/.ram – requires Real Player plug-in to display these files

.qt - requires QuickTime plug-in to display these files

Here are some common file extensions for Microsoft Office files:

.doc – Microsoft Word document – requires Microsoft Word to be installed on the computer to read or edit the file

.rtf – rich text format – universal word processing document – can be read and/or edited with any word processing software

.wpd – Word Perfect document – requires Word Perfect to be installed on the computer to read or edit the file

.pub – is a Microsoft Publisher file and requires Microsoft Publisher to be installed on the computer to read and/or edit the file

.ppt – Microsoft PowerPoint presentation and requires Microsoft Publisher to be installed on the computer to read and/or edit the file

.pps – Microsoft PowerPoint slide show and requires Microsoft Publisher to be installed on the computer to read and/or edit the file

.xls – Microsoft Excel Spreadsheet file and requires Microsoft Excel to be installed on the computer to read and/or edit the file

.xlr – Microsoft WORKS spreadsheet file and requires Microsoft WORKS to be installed on the computer to read and/or edit the file

.mdb – Microsoft Access database file and requires Microsoft Access to be installed on the computer to read and/or edit the file