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

ASF file extension

Advanced Systems Format File

Video Files

BIN file extension

Binary Disc Image

Disk Image Files

CSS file extension

Cascading Style Sheet

Web Files

DRV file extension

Device Driver

System Files

FNT file extension

Windows Font File

Font Files

ICO file extension

Icon File

System Files

JSP file extension

Java Server Page

Web Files

MSI file extension

Windows Installer Package

Misc Files

PL file extension

Perl Script

Developer Files

PY file extension

Python Script

Developer Files

RA file extension

Real Audio File

Audio Files

SRT file extension

SubRip Subtitle File

Video Files

VCD file extension

Virtual CD

Disk Image Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files

3GP file extension

3GPP Multimedia File

Video Files