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

ACCDB file extension

Access 2007 Database File

Database Files

CRDOWNLOAD file extension

Chrome Partially Downloaded File

Misc Files

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

DMG file extension

Mac OS X Disk Image

Disk Image Files

GZ file extension

Gnu Zipped Archive

Compressed Files

H file extension

C/C++/Objective-C Header File

Developer Files

MDB file extension

Microsoft Access Database

Database Files

MOBI file extension

Mobipocket eBook

eBook Files

PAGES file extension

Pages Document

Text Files

PL file extension

Perl Script

Developer Files

PPT file extension

PowerPoint Presentation

Data Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

PSPIMAGE file extension

PaintShop Pro Image

Raster Image Files

RTF file extension

Rich Text Format File

Text Files

3DM file extension

Rhino 3D Model

3D Image Files