Single-pole: A standard ON/OFF switch that controls one fixture from one location. 
      3-Way: A 3-way switch controls one fixture from two locations. In three-way applications, two 3-way switches are required. 
      4-Way: A 4-way switch allows you to control one fixture from three locations. In four-way applications, one 4-way switch and two 3-way switches are required.

Also see the below form for your reference.