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

APK file extension

Android Package File

Executable Files

ASP file extension

Active Server Page

Web Files

BIN file extension

Binary Disc Image

Disk Image Files

DTD file extension

Document Type Definition File

Developer Files

EXE file extension

Windows Executable File

Executable Files

IFF file extension

Interchange File Format

Audio Files

KEY file extension

Keynote Presentation

Data Files

LOG file extension

Log File

Text Files

MPA file extension

MPEG-2 Audio File

Audio Files

ODT file extension

OpenDocument Text Document

Text Files

SQL file extension

Structured Query Language Data File

Database Files

TAR file extension

Consolidated Unix File Archive

Data Files

TOAST file extension

Toast Disc Image

Disk Image Files

XML file extension

XML File

Data Files

3DS file extension

3D Studio Scene

3D Image Files