A fire alarm system is an active fire protection system that automatically (or manually) detects a fire, or the effects of fire, and performs one or more of the following functions: • warns the building occupants via audible (and possibly visual) alerting devices 

• automatically summons the fire service (if remotely connected) 
• indicates the location/zone of the activated detector or manual call point 
• self-supervises for fault conditions 
• resists false activation due to typical non-fire phenomena 
• initiates ancillary fire-related control functions in the building (e.g. lift recall, air conditioning shutdown, smoke-stop door release). 

A fire alarm system will typically include:

• manual call points
• smoke and/or heat detectors
• control and indicating equipment
• fire alerting devices
• safety control outputs
• power supplies and batteries
• interconnection wiring.

If connected to a remote receiving centre it will also include remote signalling equipment.

The protected premises will generally be subdivided into detection “Zones”. The area of a Zone is typically limited to what can readily be searched by a fire fighter in a short period of time. 

An indication of the fire’s approximate location will be provided to attending fire fighters on an “index” map of the building. Analogue Addressable Systems are also able to display a text description of the location of the activated detector or manual call point.