What is the cite attribute for?

Question

The cite attribute specifies the address of the source of the quoted text, I think, but who uses this information?

For example:

Answer 1

W3C has this to say:

The value of this attribute is a URI that designates a source document or message. This attribute is intended to give information about the source from which the quotation was borrowed.

It's not visible and I can't think of anywhere it's used except perhaps by search engines.