Name: extension

Synonyms: file extension,extension

Type: glossary

Description:
One or more <character|characters> following a period at the end of a file name, that indicate what type of <file> it is. 
 
<Windows|Windows systems> determine which application owns a <file> based on the <file|file's> extension. <OS X|OS X systems> determine a file's type based on its extension.

References: character (glossary), Windows (glossary), file (glossary), OS X (glossary)

Tags: file system
