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

C file extension

C/C++ Source Code File

Developer Files

CBR file extension

Comic Book RAR Archive

Compressed Files

CSV file extension

Comma Separated Values File

Data Files

DAT file extension

Data File

Data Files

DMP file extension

Windows Memory Dump

System Files

EPUB file extension

Open eBook File

eBook Files

MID file extension

MIDI File

Audio Files

MOBI file extension

Mobipocket eBook

eBook Files

PHP file extension

PHP Source Code File

Web Files

PNG file extension

Portable Network Graphic

Raster Image Files

PSD file extension

Adobe Photoshop Document

Raster Image Files

PY file extension

Python Script

Developer Files

SYS file extension

Windows System File

System Files

3GP file extension

3GPP Multimedia File

Video Files