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

PCT file extension

Picture File

Layout Files

DAT file extension

Data File

Data Files

JAVA file extension

Java Source Code File

Developer Files

MSI file extension

Windows Installer Package

Misc Files

CSV file extension

Comma Separated Values File

Data Files

KML file extension

Keyhole Markup Language File

GIS Files

ASX file extension

Microsoft ASF Redirector File

Video Files

CER file extension

Internet Security Certificate

Web Files

MDF file extension

Media Disc Image File

Disk Image Files

UUE file extension

Uuencoded File

Encoded Files

7Z file extension

7-Zip Compressed File

Compressed Files

PDB file extension

Program Database

Database Files

GPX file extension

GPS Exchange File

GIS Files

FLV file extension

Flash Video File

Video Files

APK file extension

Android Package File

Executable Files