1. The first stage is the detection stage, where the system detects smoke, heat, or other signs of a fire.
  2. The second stage is the alarm stage, where the system alerts occupants of the building of the fire. This can be done through audible and/or visual alarms.
  3. The third stage, which is optional, is the suppression stage, where the system automatically activates fire suppression equipment, such as sprinklers or fire extinguishers, to extinguish the fire.