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

AVI file extension

Audio Video Interleave File

Video Files

AZW file extension

Amazon Kindle eBook File

eBook Files

CER file extension

Internet Security Certificate

Web Files

COM file extension

DOS Command File

Executable Files

CSV file extension

Comma Separated Values File

Data Files

GBR file extension

Gerber File

Data Files

JAR file extension

Java Archive File

Executable Files

MDF file extension

Media Disc Image File

Disk Image Files

MP4 file extension

MPEG-4 Video File

Video Files

PCT file extension

Picture File

Layout Files

PPT file extension

PowerPoint Presentation

Data Files

TGA file extension

Targa Graphic

Raster Image Files

TIFF file extension

Tagged Image File Format

Raster Image Files

VOB file extension

DVD Video Object File

Video Files