Before getting into the nitty gritty of watering systems we thought it would be useful to define it.
What is an automatic watering system
An automatic watering system can be anything that helps you water your plants without having to pour the water manually.
It can be as low tech as a bottle set in the soil, a water line with a couple drippers. You can also find higher tech systems using humidity sensors in the soil connected to a Raspberry or an Arduino. The watering will start when the soil levels are too low.