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

CBR file extension

Comic Book RAR Archive

Compressed Files

CSR file extension

Certificate Signing Request File

Web Files

EPUB file extension

Open eBook File

eBook Files

GZ file extension

Gnu Zipped Archive

Compressed Files

IBOOKS file extension

Multi-Touch iBook

Data Files

JAVA file extension

Java Source Code File

Developer Files

KEY file extension

Keynote Presentation

Data Files

LOG file extension

Log File

Text Files

MID file extension

MIDI File

Audio Files

PDF file extension

Portable Document Format File

Layout Files

PY file extension

Python Script

Developer Files

SLN file extension

Visual Studio Solution File

Developer Files

TAX2012 file extension

TurboTax 2012 Tax Return

Data Files

TGA file extension

Targa Graphic

Raster Image Files

YUV file extension

YUV Encoded Image File

Raster Image Files