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

ASPX file extension

Active Server Page Extended File

Web Files

AVI file extension

Audio Video Interleave File

Video Files

CPL file extension

Windows Control Panel Item

System Files

FON file extension

Generic Font File

Font Files

ICNS file extension

Mac OS X Icon Resource File

System Files

ISO file extension

Disc Image File

Disk Image Files

JAR file extension

Java Archive File

Executable Files

JAVA file extension

Java Source Code File

Developer Files

MDB file extension

Microsoft Access Database

Database Files

MP4 file extension

MPEG-4 Video File

Video Files

MPG file extension

MPEG Video File

Video Files

PAGES file extension

Pages Document

Text Files

PY file extension

Python Script

Developer Files

SRT file extension

SubRip Subtitle File

Video Files

TEX file extension

LaTeX Source Document

Text Files