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

CPP file extension

C++ Source Code File

Developer Files

CUR file extension

Windows Cursor

System Files

DAT file extension

Data File

Data Files

DB file extension

Database File

Database Files

DOC# file extension

Microsoft Word Document

Text Files

JAR file extension

Java Archive File

Executable Files

MOV file extension

Apple QuickTime Movie

Video Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

PDF file extension

Portable Document Format File

Layout Files

PRF file extension

Outlook Profile File

Settings Files

TIFF file extension

Tagged Image File Format

Raster Image Files

TTF file extension

TrueType Font

Font Files

VOB file extension

DVD Video Object File

Video Files

XML file extension

XML File

Data Files