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

7Z file extension

7-Zip Compressed File

Compressed Files

FNT file extension

Windows Font File

Font Files

LOG file extension

Log File

Text Files

APP file extension

Mac OS X Application

Executable Files

SH file extension

Bash Shell Script

Developer Files

KML file extension

Keyhole Markup Language File

GIS Files

TXT file extension

Plain Text File

Text Files

GED file extension

GEDCOM Genealogy Data File

Data Files

XCODEPROJ file extension

Xcode Project

Developer Files

TGA file extension

Targa Graphic

Raster Image Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files

FLV file extension

Flash Video File

Video Files

RTF file extension

Rich Text Format File

Text Files

JAVA file extension

Java Source Code File

Developer Files

VCXPROJ file extension

Visual C++ Project

Developer Files