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

ACCDB file extension

Access 2007 Database File

Database Files

ASF file extension

Advanced Systems Format File

Video Files

GADGET file extension

Windows Gadget

Executable Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

ICS file extension

iCalendar File

Misc Files

ISO file extension

Disc Image File

Disk Image Files

JAR file extension

Java Archive File

Executable Files

MDF file extension

Media Disc Image File

Disk Image Files

MOBI file extension

Mobipocket eBook

eBook Files

MOV file extension

Apple QuickTime Movie

Video Files

PIF file extension

Program Information File

Executable Files

SQL file extension

Structured Query Language Data File

Database Files

TXT file extension

Plain Text File

Text Files

WPD file extension

WordPerfect Document

Text Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files