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

AZW file extension

Amazon Kindle eBook File

eBook Files

BIN file extension

Binary Disc Image

Disk Image Files

CSV file extension

Comma Separated Values File

Data Files

EPUB file extension

Open eBook File

eBook Files

KMZ file extension

Google Earth Placemark File

GIS Files

MDF file extension

Media Disc Image File

Disk Image Files

PCT file extension

Picture File

Layout Files

PRF file extension

Outlook Profile File

Settings Files

ROM file extension

N64 Game ROM File

Game Files

SLN file extension

Visual Studio Solution File

Developer Files

SQL file extension

Structured Query Language Data File

Database Files

SVG file extension

Scalable Vector Graphics File

Vector Image Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files

ZIPX file extension

Extended Zip File

Compressed Files