Null Modem?

[Princey]

One of the questions for my assignment is "Explain why the cable connecting the two COM ports is referred to as a “null modem” cable". I know how a null modem works etc but I just can't find why it is called a null modem. Does anybody know?

EDIT: Is it possible to share a Dial-up connection between two computers?

 

[basmic]

Because there is no network.

The cable simply connects one computer to another, without the need for networking devices - such as a modem or network card.