What is the name given to the three or four letter identifier at the end of a file name?

The term used to describe the three or four letter identifier at the end of a file name is known as the file extension. This extension is important because it indicates the file type and associates it with the appropriate application for opening or editing that file. For instance, a file ending in .docx is recognized as a Microsoft Word document, while a file with a .jpg extension is identified as an image file. This helps both users and the operating system understand how to handle the file correctly.

In contrast, file encryption refers to the process of securing files by converting their contents into a format that is unreadable without a specific key or password. File metadata consists of additional information about the file, such as the author, creation date, and file size, but does not indicate the type of file itself. File format is a broader term that encompasses how data is structured within a file but is not specifically related to the identifier at the end of the file name. Hence, the correct understanding of file extension is vital for recognizing and utilizing files appropriately in computing environments.