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

CBR file extension

Comic Book RAR Archive

Compressed Files

CSV file extension

Comma Separated Values File

Data Files

CUR file extension

Windows Cursor

System Files

DEB file extension

Debian Software Package

Compressed Files

FLV file extension

Flash Video File

Video Files

FON file extension

Generic Font File

Font Files

INI file extension

Windows Initialization File

Settings Files

ISO file extension

Disc Image File

Disk Image Files

LOG file extension

Log File

Text Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

PSPIMAGE file extension

PaintShop Pro Image

Raster Image Files

TAR file extension

Consolidated Unix File Archive

Data Files

XLR file extension

Works Spreadsheet

Spreadsheet Files

XML file extension

XML File

Data Files