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

CUE file extension

Cue Sheet File

Disk Image Files

7Z file extension

7-Zip Compressed File

Compressed Files

FON file extension

Generic Font File

Font Files

PIF file extension

Program Information File

Executable Files

EPUB file extension

Open eBook File

eBook Files

PPS file extension

PowerPoint Slide Show

Data Files

UUE file extension

Uuencoded File

Encoded Files

PDF file extension

Portable Document Format File

Layout Files

ASPX file extension

Active Server Page Extended File

Web Files

SQL file extension

Structured Query Language Data File

Database Files

CSV file extension

Comma Separated Values File

Data Files

ICNS file extension

Mac OS X Icon Resource File

System Files

EPS file extension

Encapsulated PostScript File

Vector Image Files

JAR file extension

Java Archive File

Executable Files

HTM file extension

Hypertext Markup Language File

Web Files