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

AZW file extension

Amazon Kindle eBook File
eBook Files

CER file extension

Internet Security Certificate
Web Files

GED file extension

GEDCOM Genealogy Data File
Data Files

GZ file extension

Gnu Zipped Archive
Compressed Files

IFF file extension

Interchange File Format
Audio Files

MSG file extension

Outlook Mail Message
Text Files

OTF file extension

OpenType Font
Font Files

PIF file extension

Program Information File
Executable Files

PRF file extension

Outlook Profile File
Settings Files

RA file extension

Real Audio File
Audio Files

RM file extension

Real Media File
Video Files

RPM file extension

Red Hat Package Manager File
Compressed Files

RTF file extension

Rich Text Format File
Text Files

WSF file extension

Windows Script File
Executable Files

XML file extension

XML File
Data Files