Or flip a switch at the bottom of the stairs, and then again at the top. The next person, coming from either direction, must be able to turn the light on again. That's where 3-way switches come in.

Add/Relocate 3 Way Switch without Rewiring - Simply wired between the power and lighting fixtures; no complex in-wall rewiring or WiFi needed to add/relocate switch, pre-programmed for immediate use.

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