Most systems will have a central controller, sensors that tell you what is happening (motion, doors opening, temperature, humidity, light, etc) and actuators that make things happen (turning on a light, switching off the TV, opening the blinds, etc).
Regardless of which technology you use in your Home Automation system, the basic building blocks and components will be similar. Most systems will have a central controller, sensors that tell you what is happening (motion, doors opening, temperature, humidity, light, etc) and actuators that make things happen (turning on a light, switching off the TV, opening the blinds, etc).