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

ASP file extension

Active Server Page

Web Files

LUA file extension

Lua Source File

Developer Files

GED file extension

GEDCOM Genealogy Data File

Data Files

FLV file extension

Flash Video File

Video Files

7Z file extension

7-Zip Compressed File

Compressed Files

LNK file extension

Windows File Shortcut

System Files

XML file extension

XML File

Data Files

XLS file extension

Excel Spreadsheet

Spreadsheet Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files

TXT file extension

Plain Text File

Text Files

CUR file extension

Windows Cursor

System Files

GAM file extension

Saved Game File

Game Files

SH file extension

Bash Shell Script

Developer Files

C file extension

C/C++ Source Code File

Developer Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files