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

AZW file extension

Amazon Kindle eBook File

eBook Files

BIN file extension

Binary Disc Image

Disk Image Files

CPL file extension

Windows Control Panel Item

System Files

CUR file extension

Windows Cursor

System Files

DRV file extension

Device Driver

System Files

GBR file extension

Gerber File

Data Files

ISO file extension

Disc Image File

Disk Image Files

MOBI file extension

Mobipocket eBook

eBook Files

MOV file extension

Apple QuickTime Movie

Video Files

PDF file extension

Portable Document Format File

Layout Files

RTF file extension

Rich Text Format File

Text Files

TMP file extension

Temporary File

Backup Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files

ZIPX file extension

Extended Zip File

Compressed Files