A Building Management System (BMS), or Building Automation System (BAS), is a smart system that monitors, manages and optimizes the mechanical, electrical, and safety systems in a building. Whenever individuals go querying about what is BMS system, how BMS functions, what is  BMS system in HVAC, and why BMS is necessary, the response always comes around to integration, automation and efficiency. A Building Management System integrates every  processes in a single dashboard and allows to manage: HVAC Lighting systems Supplying water Elevating Devices Fire alarm systems Energy meters and submeters Security and access control Parking and outside illumination Sustainable Energy Sources Enhanced Building Management System , what is BMS system allows these systems to talk to one another without complications using BACnet, Modbus, LonWorks, KNX, and IoT APIs. A smart BMS helps to attain comfort, and quality of air, cuts energy use and increases safety, and longevity of building asset. It is a key component of every modern building. BMS also uses I/O modules for exchanging digital inputs and outputs.