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

ASPX file extension

Active Server Page Extended File

Web Files

CSV file extension

Comma Separated Values File

Data Files

DBF file extension

Database File

Database Files

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

IBOOKS file extension

Multi-Touch iBook

Data Files

JAVA file extension

Java Source Code File

Developer Files

JS file extension

JavaScript File

Web Files

PCT file extension

Picture File

Layout Files

PKG file extension

Mac OS X Installer Package

Compressed Files

PS file extension

PostScript File

Vector Image Files

TARGZ file extension

Compressed Tarball File

Compressed Files

UUE file extension

Uuencoded File

Encoded Files

VOB file extension

DVD Video Object File

Video Files

XLR file extension

Works Spreadsheet

Spreadsheet Files