There are two types of main circuits that are available wherein electricity can pass through, and these are parallel and series circuits. When you have a parallel circuit, all of the bulbs that are connected to one switch will all turn on at the same time when you turn on the switch.
The moment that you turn the switch off, all of the lights will also turn off. When you are using a series circuit, this means that you are going to have different switches for the various types of lights that are available. For example, if you would like to turn on one light and turn off another light, this will always be possible.