File extensions – definition and basic information


File extensions are the integral parts of the files that are on each computer. Often, when working on a computer, we encounter a wide range of files, such as docx, ppt, part, mp3 or rmvb. We realize that they are there – but we often do not know what they are for on our computer.

File extension, also known as the filename extension is a suffix added to the name of a computer file, usually consisting of a number of characters placed after the last dot in the filename, which gives us information about its coding. In other words a file extension is a file format. It allows the operating system (e.g. Windows) to recognize what program it should try to open the file.

In the table below you will find a random selection of popular file extensions.


File extension The full name of the file Category

HTML file extension

Hypertext Markup Language File

Web Files

FLA file extension

Adobe Flash Animation

Developer Files

7Z file extension

7-Zip Compressed File

Compressed Files

DMG file extension

Mac OS X Disk Image

Disk Image Files

TIF file extension

Tagged Image File

Raster Image Files

SH file extension

Bash Shell Script

Developer Files

DTD file extension

Document Type Definition File

Developer Files

3G2 file extension

3GPP2 Multimedia File

Video Files

TIFF file extension

Tagged Image File Format

Raster Image Files

PRF file extension

Outlook Profile File

Settings Files

APK file extension

Android Package File

Executable Files

MIM file extension

Multi-Purpose Internet Mail Message File

Encoded Files

PHP file extension

PHP Source Code File

Web Files

AZW file extension

Amazon Kindle eBook File

eBook Files

ASF file extension

Advanced Systems Format File

Video Files