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

DAT file extension

Data File

Data Files

DBF file extension

Database File

Database Files

DMP file extension

Windows Memory Dump

System Files

EPUB file extension

Open eBook File

eBook Files

GZ file extension

Gnu Zipped Archive

Compressed Files

INDD file extension

Adobe InDesign Document

Layout Files

JSP file extension

Java Server Page

Web Files

MDB file extension

Microsoft Access Database

Database Files

MID file extension

MIDI File

Audio Files

PHP file extension

PHP Source Code File

Web Files

PSD file extension

Adobe Photoshop Document

Raster Image Files

TARGZ file extension

Compressed Tarball File

Compressed Files

TXT file extension

Plain Text File

Text Files

UUE file extension

Uuencoded File

Encoded Files

WMV file extension

Windows Media Video File

Video Files