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

PSPIMAGE file extension

PaintShop Pro Image

Raster Image Files

RM file extension

Real Media File

Video Files

ODT file extension

OpenDocument Text Document

Text Files

DNG file extension

Digital Negative Image File

Camera Raw Files

MOBI file extension

Mobipocket eBook

eBook Files

7Z file extension

7-Zip Compressed File

Compressed Files

THM file extension

Thumbnail Image File

Raster Image Files

MIM file extension

Multi-Purpose Internet Mail Message File

Encoded Files

TMP file extension

Temporary File

Backup Files

CPL file extension

Windows Control Panel Item

System Files

KMZ file extension

Google Earth Placemark File

GIS Files

ASP file extension

Active Server Page

Web Files

MDB file extension

Microsoft Access Database

Database Files

PKG file extension

Mac OS X Installer Package

Compressed Files

WSF file extension

Windows Script File

Executable Files