You might have come to a house where you have two switches controlling the same lightbulb and you wonder how that was done. That’s very easy to know, 2 Single-Pole,Double-Throw (SPDT) switches or in a simple term two, 2-way switches were used.
The schematic below shows how the connection is made. You should see clearly now why either switch will reverse the state of the LED from on to off or off to on. This same circuit is used in houses where you have two switches controlling the same lightbulb. Though the wires in a house are much longer, and they but their connections are still the same, they could be represented with the same basic schematic.
Note:A schematic doesn’t tell you exactly where to place the components. It just shows you how to join them together. Different people use slightly different schematic symbols to convey the same thing.