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

AZW file extension

Amazon Kindle eBook File

eBook Files

CAB file extension

Windows Cabinet File

System Files

CGI file extension

Common Gateway Interface Script

Executable Files

DBF file extension

Database File

Database Files

FLV file extension

Flash Video File

Video Files

GBR file extension

Gerber File

Data Files

IBOOKS file extension

Multi-Touch iBook

Data Files

JAR file extension

Java Archive File

Executable Files

KMZ file extension

Google Earth Placemark File

GIS Files

MDB file extension

Microsoft Access Database

Database Files

MDF file extension

Media Disc Image File

Disk Image Files

MP4 file extension

MPEG-4 Video File

Video Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

SRT file extension

SubRip Subtitle File

Video Files

SWF file extension

Shockwave Flash Movie

Video Files