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

ZIPX file extension

Extended Zip File

Compressed Files

SYS file extension

Windows System File

System Files

CFM file extension

ColdFusion Markup File

Web Files

FON file extension

Generic Font File

Font Files

CUR file extension

Windows Cursor

System Files

DAT file extension

Data File

Data Files

JSP file extension

Java Server Page

Web Files

DEM file extension

Video Game Demo File

Game Files

MOBI file extension

Mobipocket eBook

eBook Files

7Z file extension

7-Zip Compressed File

Compressed Files

PSPIMAGE file extension

PaintShop Pro Image

Raster Image Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files

PDF file extension

Portable Document Format File

Layout Files

SQL file extension

Structured Query Language Data File

Database Files

LOG file extension

Log File

Text Files