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

7Z file extension

7-Zip Compressed File

Compressed Files

ICNS file extension

Mac OS X Icon Resource File

System Files

ODT file extension

OpenDocument Text Document

Text Files

JSP file extension

Java Server Page

Web Files

RM file extension

Real Media File

Video Files

ASPX file extension

Active Server Page Extended File

Web Files

PDF file extension

Portable Document Format File

Layout Files

PAGES file extension

Pages Document

Text Files

RPM file extension

Red Hat Package Manager File

Compressed Files

3G2 file extension

3GPP2 Multimedia File

Video Files

ICS file extension

iCalendar File

Misc Files

MPG file extension

MPEG Video File

Video Files

CSV file extension

Comma Separated Values File

Data Files

PS file extension

PostScript File

Vector Image Files

WPD file extension

WordPerfect Document

Text Files