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

AIF file extension

Audio Interchange File Format

Audio Files

CSV file extension

Comma Separated Values File

Data Files

DMP file extension

Windows Memory Dump

System Files

DRV file extension

Device Driver

System Files

DTD file extension

Document Type Definition File

Developer Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

MOBI file extension

Mobipocket eBook

eBook Files

OTF file extension

OpenType Font

Font Files

PPT file extension

PowerPoint Presentation

Data Files

PSPIMAGE file extension

PaintShop Pro Image

Raster Image Files

RPM file extension

Red Hat Package Manager File

Compressed Files

SYS file extension

Windows System File

System Files

TAX2012 file extension

TurboTax 2012 Tax Return

Data Files

THM file extension

Thumbnail Image File

Raster Image Files

WAV file extension

WAVE Audio File

Audio Files