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

ASP file extension

Active Server Page

Web Files

BAT file extension

DOS Batch File

Executable Files

CBR file extension

Comic Book RAR Archive

Compressed Files

DLL file extension

Dynamic Link Library

System Files

DRV file extension

Device Driver

System Files

EPS file extension

Encapsulated PostScript File

Vector Image Files

ICO file extension

Icon File

System Files

LOG file extension

Log File

Text Files

ODT file extension

OpenDocument Text Document

Text Files

OTF file extension

OpenType Font

Font Files

PDF file extension

Portable Document Format File

Layout Files

PIF file extension

Program Information File

Executable Files

RAR file extension

WinRAR Compressed Archive

Compressed Files

TOAST file extension

Toast Disc Image

Disk Image Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files