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

CSR file extension

Certificate Signing Request File

Web Files

DOCX file extension

Microsoft Word Open XML Document

Text Files

GZ file extension

Gnu Zipped Archive

Compressed Files

ICO file extension

Icon File

System Files

LNK file extension

Windows File Shortcut

System Files

M file extension

Objective-C Implementation File

Developer Files

MIM file extension

Multi-Purpose Internet Mail Message File

Encoded Files

MOV file extension

Apple QuickTime Movie

Video Files

PCT file extension

Picture File

Layout Files

TIF file extension

Tagged Image File

Raster Image Files

TMP file extension

Temporary File

Backup Files

VCD file extension

Virtual CD

Disk Image Files

XLR file extension

Works Spreadsheet

Spreadsheet Files