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

ACCDB file extension

Access 2007 Database File

Database Files

BAK file extension

Backup File

Backup Files

BMP file extension

Bitmap Image File

Raster Image Files

CER file extension

Internet Security Certificate

Web Files

DBF file extension

Database File

Database Files

EPUB file extension

Open eBook File

eBook Files

GZ file extension

Gnu Zipped Archive

Compressed Files

IBOOKS file extension

Multi-Touch iBook

Data Files

JPG file extension

JPEG Image

Raster Image Files

M4V file extension

iTunes Video File

Video Files

RAR file extension

WinRAR Compressed Archive

Compressed Files

SVG file extension

Scalable Vector Graphics File

Vector Image Files

SYS file extension

Windows System File

System Files

VCXPROJ file extension

Visual C++ Project

Developer Files

XCODEPROJ file extension

Xcode Project

Developer Files