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

BAT file extension

DOS Batch File

Executable Files

COM file extension

DOS Command File

Executable Files

EPS file extension

Encapsulated PostScript File

Vector Image Files

EPUB file extension

Open eBook File

eBook Files

GAM file extension

Saved Game File

Game Files

JAVA file extension

Java Source Code File

Developer Files

JPG file extension

JPEG Image

Raster Image Files

KEY file extension

Keynote Presentation

Data Files

PDF file extension

Portable Document Format File

Layout Files

SDF file extension

Standard Data File

Data Files

SQL file extension

Structured Query Language Data File

Database Files

SRT file extension

SubRip Subtitle File

Video Files

SYS file extension

Windows System File

System Files

TIFF file extension

Tagged Image File Format

Raster Image Files

VCF file extension

vCard File

Data Files