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

AIF file extension

Audio Interchange File Format

Audio Files

CSV file extension

Comma Separated Values File

Data Files

DTD file extension

Document Type Definition File

Developer Files

EPUB file extension

Open eBook File

eBook Files

FNT file extension

Windows Font File

Font Files

IFF file extension

Interchange File Format

Audio Files

M file extension

Objective-C Implementation File

Developer Files

MIM file extension

Multi-Purpose Internet Mail Message File

Encoded Files

MPG file extension

MPEG Video File

Video Files

TIFF file extension

Tagged Image File Format

Raster Image Files

UUE file extension

Uuencoded File

Encoded Files

WMA file extension

Windows Media Audio File

Audio Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files

ZIPX file extension

Extended Zip File

Compressed Files