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

CBR file extension

Comic Book RAR Archive

Compressed Files

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

DLL file extension

Dynamic Link Library

System Files

DOC# file extension

Microsoft Word Document

Text Files

EPUB file extension

Open eBook File

eBook Files

GBR file extension

Gerber File

Data Files

NES file extension

Nintendo (NES) ROM File

Game Files

PDB file extension

Program Database

Database Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

SDF file extension

Standard Data File

Data Files

SH file extension

Bash Shell Script

Developer Files

TXT file extension

Plain Text File

Text Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files

XLR file extension

Works Spreadsheet

Spreadsheet Files

ZIP file extension

Zipped File

Compressed Files