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

It mentions that if a light fixture is between ... conventional colors? In the diagram on the link they are using a three conductor cable after the first three way switch. Black, Red, and White ...

My house was built in the 50s, with wiring from ... the existing switch is a 3-way switch? But I read these have to be used in pairs, except no other switch affects this light.