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

CRDOWNLOAD file extension

Chrome Partially Downloaded File

Misc Files

CSV file extension

Comma Separated Values File

Data Files

EPUB file extension

Open eBook File

eBook Files

IBOOKS file extension

Multi-Touch iBook

Data Files

INDD file extension

Adobe InDesign Document

Layout Files

MP4 file extension

MPEG-4 Video File

Video Files

ODT file extension

OpenDocument Text Document

Text Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

RPM file extension

Red Hat Package Manager File

Compressed Files

RSS file extension

Rich Site Summary

Web Files

SQL file extension

Structured Query Language Data File

Database Files

TARGZ file extension

Compressed Tarball File

Compressed Files

TGA file extension

Targa Graphic

Raster Image Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files