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

PPS file extension

PowerPoint Slide Show

Data Files

ACCDB file extension

Access 2007 Database File

Database Files

DWG file extension

AutoCAD Drawing Database File

CAD Files

APP file extension

Mac OS X Application

Executable Files

DTD file extension

Document Type Definition File

Developer Files

ICS file extension

iCalendar File

Misc Files

JAVA file extension

Java Source Code File

Developer Files

JAR file extension

Java Archive File

Executable Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

3GP file extension

3GPP Multimedia File

Video Files

PCT file extension

Picture File

Layout Files

DAT file extension

Data File

Data Files

GBR file extension

Gerber File

Data Files

7Z file extension

7-Zip Compressed File

Compressed Files

EXE file extension

Windows Executable File

Executable Files