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

CSV file extension

Comma Separated Values File
Data Files

CUE file extension

Cue Sheet File
Disk Image Files

DRV file extension

Device Driver
System Files

ICS file extension

iCalendar File
Misc Files

ISO file extension

Disc Image File
Disk Image Files

JSP file extension

Java Server Page
Web Files

M3U file extension

Media Playlist File
Audio Files

MDB file extension

Microsoft Access Database
Database Files

MOBI file extension

Mobipocket eBook
eBook Files

PKG file extension

Mac OS X Installer Package
Compressed Files

TEX file extension

LaTeX Source Document
Text Files

TTF file extension

TrueType Font
Font Files

VCF file extension

vCard File
Data Files

XLR file extension

Works Spreadsheet
Spreadsheet Files

XML file extension

XML File
Data Files