Stop walking across a dark room to turn on the light. Install a 3-way switch and control lights from two locations.

In the diagram on the link they are using a three conductor cable after the first three way switch. Black ... They shared the white neutral wire. It sounds like you got it figured out, but ...

A light switch is the simplest of electrical devices. Flip the switch, electricity flows. Flip it again, electricity stops. Lights on, lights off. That's great for a small room with one entrance.