Building Automation Systems (BAS) are systems that are designed to control and monitor the mechanical, electrical, and other systems in a building. They are used to improve energy efficiency, increase safety, and reduce operational costs. BAS are comprised of hardware, software, and communication networks that enable the automation of various building systems. The hardware includes sensors, controllers, and actuators that are connected to the system, while the software is used to control the system. The communication networks are used to connect the system to other systems, such as the Internet, to allow for remote monitoring and control. BAS can be used to control lighting, heating, ventilation, air conditioning, security, and other systems. They can also be used to monitor energy usage, detect problems, and provide alerts when necessary. BAS can help to reduce energy costs, improve safety, and provide a more comfortable environment for occupants.