A file extension, or file name extension, is the letters immediately shown after the last period in a file name. For example, the file extension.txt has an extension of .txt. This extension allows the ...

(DOCument file) The default file format in a version of Word, Microsoft's word processing application prior to Microsoft Office 2007. DOC files use a .DOC extension and differ from text files (.TXT ...

A file extension is a suffix that is added to the end of a file name after a dot. It is usually two to four letters long. File extensions help Windows and other operating systems to know the standard ...