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

AI file extension

Adobe Illustrator File

Vector Image Files

APP file extension

Mac OS X Application

Executable Files

CBR file extension

Comic Book RAR Archive

Compressed Files

CER file extension

Internet Security Certificate

Web Files

CRDOWNLOAD file extension

Chrome Partially Downloaded File

Misc Files

EPUB file extension

Open eBook File

eBook Files

FLA file extension

Adobe Flash Animation

Developer Files

KMZ file extension

Google Earth Placemark File

GIS Files

M4V file extension

iTunes Video File

Video Files

PCT file extension

Picture File

Layout Files

RPM file extension

Red Hat Package Manager File

Compressed Files

RSS file extension

Rich Site Summary

Web Files

UUE file extension

Uuencoded File

Encoded Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files

3G2 file extension

3GPP2 Multimedia File

Video Files