What are file name extensions
File names in Windows Operating Systems, including Windows Server operating systems are made of two parts. First part is the name of the file and the second part is called as the file extension. The purpose of the second part is to identify the file type. The first part and the second part are separated by a period ( . ) character.
For example, the filename monthly-expenses.xlsx has a file name extension xlsx. The file extension in this case is xlsx, which shows the file is a Microsoft Excel file. When you install the Excel app in your computer, the Excel installation program will register the xlsx extension in your computer as a known extension, so that the Operating System can open the file with the relevant app.
Usually the file extensions (second part of the file name) are made of three or four characters. But single–character and five–character file extensions are also available. Examples of single–character and five–character file extensions are .c (C language file extension) and .accdb (Access 2007 database file extension).
I suggest you to visit the following links also, to learn more about the following topics.
• What are known file extensions and how to view known file extensions
• How to associate a file name extension with an app
• Hide or Show known file name extensions in Windows Server 2025
Some important file extensions are listed in the following table.
| File Extension | Short Description | Length (Number of chars ) |
|---|---|---|
| 7z | Compressed file extension | 2 |
| accdb | Microsoft Access database file format | 5 |
| ai | Adobe Illustrator file extension | 2 |
| bat | Batch commands | 3 |
| bmp | Microsoft Bitmap image file | 3 |
| c | C programming language file | 1 |
| cab | Windows cabinet file | 3 |
| cap | Wireshark capture files | 3 |
| class | Java bytecode file extension | 5 |
| com | DOS executable file (A type of early executable file) | 3 |
| cpp | C++ programming language file | 3 |
| css | Cascading Style Sheet file | 3 |
| dat | Data file | 3 |
| dll | Dynamic–link library file | 3 |
| doc | Microsoft Word document before Word 2007 | 3 |
| docx | Microsoft Word document | 4 |
| exe | Windows executable file | 3 |
| flac, mp4, mov, avi, mkv, swf | Video file extensions | 3 to 4 |
| gif | Graphics interchange format image file | 3 |
| gz, gzip | Unix Gzip compressed file | 8 |
| htm, html | Hypertext Markup Language file | 9 |
| inf | Setup information file | 3 |
| ini | Windows initialization file | 3 |
| jar | Java archive file | 3 |
| java | Java programming language file | 4 |
| jpeg | Joint photographic experts group image file | 4 |
| js | JavaScript file | 2 |
| mdb | Microsoft Access database file format before Access 2007 | 3 |
| msc | Microsoft console file | 3 |
| msi | Windows installer package files | 3 |
| odb | Open Offfice Database file extension | 3 |
| odg | Open Office Draw file extension | 3 |
| odp | Open Office Impress file extension | 3 |
| ods | Open Office Calc file extension | 3 |
| odt | Open Office Document file extension | 3 |
| Portable document format | 3 | |
| png | Portable network graphics image file | 3 |
| potx | Microsoft PowerPoint template | 4 |
| ppt | Microsoft PowerPoint format before PowerPoint 2007 | 3 |
| pptx | Microsoft PowerPoint presentation | 4 |
| ps | Adobe Post Script file extension | 2 |
| psd | Adobe Photoshop file | 3 |
| pub | Microsoft Publisher file | 3 |
| rar | Compressed file | 3 |
| rtf | Rich text format file extension | 3 |
| tar | Unix compressed file extension | 3 |
| tif, tiff | Tagged image format | 9 |
| tmp | Temporary data file extension | 3 |
| txt | Windows text file extension | 3 |
| vbs | VB Script file extension | 3 |
| vsd | Microsoft Visio drawing before Visio 2013 | 3 |
| vsdx | Microsoft Visio drawing file extension | 4 |
| wav, mp3, aac, m4a, ogg, oga, wma, amr, flac | Audio file extensions | 3 to 4 |
| xla | Microsoft Excel add-in or macro file | 3 |
| xlam | Microsoft Excel add-in after Excel 2007 | 4 |
| xls | Microsoft Excel document before Excel 2007 | 3 |
| xlsx | Microsoft Excel document | 4 |
| xltm | Microsoft Excel macro-enabled template after Excel 2007 | 4 |
| xltx | Microsoft Excel template after Excel 2007 | 4 |
| xml | Extensible markup language file extension | 3 |
| xslt | Extensible stylesheet language transformations file extension | 4 |
| zip | Compressed file extension | 3 |
Written by Jajish Thomas.
Last updated on 19th July, 2024.