The extension identifies the file as a certain type, readable by certain applications.
The BERNINA Manual tells us: ‘A file extension is indicated with a dot and three letter at the end of a filename, such as. A file extension is typically delimited from the filename with a full stop (period), but in some systems it is separated with spaces’. The extension indicates a characteristic of the file contents or its intended use.
Wikipedia tells us: ‘A filename extension is an identifier specified as a suffix to the name of a computer file. It is important to know what you are doing when downloading clipart, pictures or embroidery designs, loading them into V8 and/or use them via your USB stick to be embroidered.
There were many users V8, asking me to explain more about files and their formats/extensions etc.