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

XHTML file extension

Extensible Hypertext Markup Language File

Web Files

PS file extension

PostScript File

Vector Image Files

JAR file extension

Java Archive File

Executable Files

HTM file extension

Hypertext Markup Language File

Web Files

AZW file extension

Amazon Kindle eBook File

eBook Files

SAV file extension

Saved Game

Game Files

MID file extension

MIDI File

Audio Files

XLS file extension

Excel Spreadsheet

Spreadsheet Files

RM file extension

Real Media File

Video Files

7Z file extension

7-Zip Compressed File

Compressed Files

CAB file extension

Windows Cabinet File

System Files

CSR file extension

Certificate Signing Request File

Web Files

VCF file extension

vCard File

Data Files

PDF file extension

Portable Document Format File

Layout Files

RA file extension

Real Audio File

Audio Files