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

PHP file extension

PHP Source Code File

Web Files

CER file extension

Internet Security Certificate

Web Files

AI file extension

Adobe Illustrator File

Vector Image Files

ASF file extension

Advanced Systems Format File

Video Files

ICS file extension

iCalendar File

Misc Files

DEM file extension

Video Game Demo File

Game Files

7Z file extension

7-Zip Compressed File

Compressed Files

TXT file extension

Plain Text File

Text Files

VB file extension

VBScript File

Executable Files

VCD file extension

Virtual CD

Disk Image Files

CUR file extension

Windows Cursor

System Files

YUV file extension

YUV Encoded Image File

Raster Image Files

SH file extension

Bash Shell Script

Developer Files

DB file extension

Database File

Database Files

AVI file extension

Audio Video Interleave File

Video Files