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

AZW file extension

Amazon Kindle eBook File

eBook Files

BMP file extension

Bitmap Image File

Raster Image Files

CSS file extension

Cascading Style Sheet

Web Files

CSV file extension

Comma Separated Values File

Data Files

CUE file extension

Cue Sheet File

Disk Image Files

DMP file extension

Windows Memory Dump

System Files

EPS file extension

Encapsulated PostScript File

Vector Image Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

LUA file extension

Lua Source File

Developer Files

ODT file extension

OpenDocument Text Document

Text Files

PDB file extension

Program Database

Database Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

RAR file extension

WinRAR Compressed Archive

Compressed Files

SQL file extension

Structured Query Language Data File

Database Files

TTF file extension

TrueType Font

Font Files