A file extension is three or four characters at the end of a filename, such as .DOCX, .PDF or .TXT. File extensions tell you the file type, and which programs can open it. These extensions are used in Microsoft Windows, Mac OS X and Linux Operating Systems.
.docx | Microsoft Open Word XML Document |
.doc | Microsoft Word Document |
.txt | Plain Text File |
.rtf | Revit Family Template File |
.odt | OpenOffice/StarOffice File |
.mp3 | MP3 Audio File |
.wav | Wave Audio File |
.aac | MPEG-2 Advanced Audio Coding File |
.wma | Windows Media Audio File |
.m4a | MPEG-4 Audio File |
.avi | Audio Video Interleave File |
.mp4 | MPEG-4 Video File |
.mov | Video Clip |
.flv | Video File |
.mpg | MPEG 1 System Stream |
Portable Document Format File | |
.xls | Excel Spreadsheet File |
.csv | Comma Separated Values File |
.ini | Initialization/Configuration File |
.html | Hypertext Markup Language File |