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

GED file extension

GEDCOM Genealogy Data File

Data Files

PHP file extension

PHP Source Code File

Web Files

ASPX file extension

Active Server Page Extended File

Web Files

CER file extension

Internet Security Certificate

Web Files

TMP file extension

Temporary File

Backup Files

SH file extension

Bash Shell Script

Developer Files

XLS file extension

Excel Spreadsheet

Spreadsheet Files

7Z file extension

7-Zip Compressed File

Compressed Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files

TGA file extension

Targa Graphic

Raster Image Files

APP file extension

Mac OS X Application

Executable Files

CPP file extension

C++ Source Code File

Developer Files

EPS file extension

Encapsulated PostScript File

Vector Image Files

HTM file extension

Hypertext Markup Language File

Web Files

VCF file extension

vCard File

Data Files