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

AI file extension

Adobe Illustrator File

Vector Image Files

BMP file extension

Bitmap Image File

Raster Image Files

C file extension

C/C++ Source Code File

Developer Files

CRDOWNLOAD file extension

Chrome Partially Downloaded File

Misc Files

CSR file extension

Certificate Signing Request File

Web Files

CUE file extension

Cue Sheet File

Disk Image Files

DAT file extension

Data File

Data Files

HTM file extension

Hypertext Markup Language File

Web Files

JSP file extension

Java Server Page

Web Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

PRF file extension

Outlook Profile File

Settings Files

PSPIMAGE file extension

PaintShop Pro Image

Raster Image Files

RM file extension

Real Media File

Video Files

SLN file extension

Visual Studio Solution File

Developer Files

XLR file extension

Works Spreadsheet

Spreadsheet Files