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

JS file extension

JavaScript File

Web Files

TMP file extension

Temporary File

Backup Files

7Z file extension

7-Zip Compressed File

Compressed Files

PSPIMAGE file extension

PaintShop Pro Image

Raster Image Files

JAVA file extension

Java Source Code File

Developer Files

PCT file extension

Picture File

Layout Files

CUR file extension

Windows Cursor

System Files

MPG file extension

MPEG Video File

Video Files

3DM file extension

Rhino 3D Model

3D Image Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files

DEB file extension

Debian Software Package

Compressed Files

DNG file extension

Digital Negative Image File

Camera Raw Files

CSR file extension

Certificate Signing Request File

Web Files

MAX file extension

3ds Max Scene File

3D Image Files

PPS file extension

PowerPoint Slide Show

Data Files