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

AVI file extension

Audio Video Interleave File

Video Files

BAK file extension

Backup File

Backup Files

DBF file extension

Database File

Database Files

DEB file extension

Debian Software Package

Compressed Files

JAR file extension

Java Archive File

Executable Files

JAVA file extension

Java Source Code File

Developer Files

LOG file extension

Log File

Text Files

M4V file extension

iTunes Video File

Video Files

PDB file extension

Program Database

Database Files

TARGZ file extension

Compressed Tarball File

Compressed Files

VCD file extension

Virtual CD

Disk Image Files

VOB file extension

DVD Video Object File

Video Files

WMV file extension

Windows Media Video File

Video Files

3DM file extension

Rhino 3D Model

3D Image Files

3G2 file extension

3GPP2 Multimedia File

Video Files