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

CGI file extension

Common Gateway Interface Script

Executable Files

CSR file extension

Certificate Signing Request File

Web Files

CUE file extension

Cue Sheet File

Disk Image Files

DBF file extension

Database File

Database Files

DMP file extension

Windows Memory Dump

System Files

DNG file extension

Digital Negative Image File

Camera Raw Files

MOBI file extension

Mobipocket eBook

eBook Files

OTF file extension

OpenType Font

Font Files

PHP file extension

PHP Source Code File

Web Files

PPT file extension

PowerPoint Presentation

Data Files

RTF file extension

Rich Text Format File

Text Files

TARGZ file extension

Compressed Tarball File

Compressed Files

VB file extension

VBScript File

Executable Files

3DS file extension

3D Studio Scene

3D Image Files

3G2 file extension

3GPP2 Multimedia File

Video Files