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

APP file extension

Mac OS X Application

Executable Files

ASP file extension

Active Server Page

Web Files

EPUB file extension

Open eBook File

eBook Files

GPX file extension

GPS Exchange File

GIS Files

IFF file extension

Interchange File Format

Audio Files

JAVA file extension

Java Source Code File

Developer Files

PDB file extension

Program Database

Database Files

RTF file extension

Rich Text Format File

Text Files

SDF file extension

Standard Data File

Data Files

TOAST file extension

Toast Disc Image

Disk Image Files

VCF file extension

vCard File

Data Files

XCODEPROJ file extension

Xcode Project

Developer Files

ZIP file extension

Zipped File

Compressed Files

ZIPX file extension

Extended Zip File

Compressed Files

3G2 file extension

3GPP2 Multimedia File

Video Files