What is a File Extension?

File extension is one or several letters at the end of a filename. Filename extensions usually follow a period (dot) and indicate the type of information stored in the file. For example, in the filename EDIT.COM, the extension is COM, which indicates that the file is a command file. Depending on the operating system, the punctuation separating the extension from the rest of the filename may or may not be considered part of the extension itself.


Keywords: What is File Extension, letters , filename.,extension,operating system