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

TAR file extension

Consolidated Unix File Archive

Data Files

GADGET file extension

Windows Gadget

Executable Files

7Z file extension

7-Zip Compressed File

Compressed Files

ICO file extension

Icon File

System Files

LNK file extension

Windows File Shortcut

System Files

SQL file extension

Structured Query Language Data File

Database Files

VCD file extension

Virtual CD

Disk Image Files

RPM file extension

Red Hat Package Manager File

Compressed Files

MDF file extension

Media Disc Image File

Disk Image Files

JAVA file extension

Java Source Code File

Developer Files

APK file extension

Android Package File

Executable Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

GED file extension

GEDCOM Genealogy Data File

Data Files

CER file extension

Internet Security Certificate

Web Files

BAK file extension

Backup File

Backup Files