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

AI file extension

Adobe Illustrator File

Vector Image Files

CGI file extension

Common Gateway Interface Script

Executable Files

COM file extension

DOS Command File

Executable Files

DMP file extension

Windows Memory Dump

System Files

FNT file extension

Windows Font File

Font Files

ISO file extension

Disc Image File

Disk Image Files

JSP file extension

Java Server Page

Web Files

MDB file extension

Microsoft Access Database

Database Files

PPT file extension

PowerPoint Presentation

Data Files

PS file extension

PostScript File

Vector Image Files

ROM file extension

N64 Game ROM File

Game Files

RPM file extension

Red Hat Package Manager File

Compressed Files

SAV file extension

Saved Game

Game Files

THM file extension

Thumbnail Image File

Raster Image Files

VCD file extension

Virtual CD

Disk Image Files