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

COM file extension

DOS Command File

Executable Files

CUR file extension

Windows Cursor

System Files

DNG file extension

Digital Negative Image File

Camera Raw Files

EPS file extension

Encapsulated PostScript File

Vector Image Files

LNK file extension

Windows File Shortcut

System Files

MAX file extension

3ds Max Scene File

3D Image Files

MOBI file extension

Mobipocket eBook

eBook Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

PPT file extension

PowerPoint Presentation

Data Files

PS file extension

PostScript File

Vector Image Files

TEX file extension

LaTeX Source Document

Text Files

XCODEPROJ file extension

Xcode Project

Developer Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files

3G2 file extension

3GPP2 Multimedia File

Video Files

3GP file extension

3GPP Multimedia File

Video Files