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

RPM file extension

Red Hat Package Manager File

Compressed Files

FNT file extension

Windows Font File

Font Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

FLV file extension

Flash Video File

Video Files

PART file extension

Partially Downloaded File

Misc Files

DDS file extension

DirectDraw Surface

Raster Image Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

DOC# file extension

Microsoft Word Document

Text Files

3G2 file extension

3GPP2 Multimedia File

Video Files

7Z file extension

7-Zip Compressed File

Compressed Files

GZ file extension

Gnu Zipped Archive

Compressed Files

APP file extension

Mac OS X Application

Executable Files

DOCX file extension

Microsoft Word Open XML Document

Text Files

PS file extension

PostScript File

Vector Image Files