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

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

7Z file extension

7-Zip Compressed File

Compressed Files

PSD file extension

Adobe Photoshop Document

Raster Image Files

ACCDB file extension

Access 2007 Database File

Database Files

WSF file extension

Windows Script File

Executable Files

ICO file extension

Icon File

System Files

BAT file extension

DOS Batch File

Executable Files

PKG file extension

Mac OS X Installer Package

Compressed Files

CBR file extension

Comic Book RAR Archive

Compressed Files

YUV file extension

YUV Encoded Image File

Raster Image Files

AZW file extension

Amazon Kindle eBook File

eBook Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files

SDF file extension

Standard Data File

Data Files

EPUB file extension

Open eBook File

eBook Files

APK file extension

Android Package File

Executable Files