If the fire alarm panel is the heart of the system, then the
annunciator is the interface that actually shows you what's
going on, and where. Fire alarm annunciators are used to
pinpoint the trouble spots, and help the staff monitor the
entire building. A fire alarm annunciator helps you make
decisions on whether the fire department needs to be notified
or whether the fire is small enough to be put under control by
the building security.
Think of the control panel as the main "computer" and the annunciator as the "operating system," like Windows. By reading the annunciator, the building security will be better able to judge the situation. A triggered fire alarm may not necessarily mean that there is a fire spiralling out of control. For example, a person lighting a cigarette could trigger a false alarm.
All the devices in the entire system are wired and interconnected on the annunciator, making it easy to get a reading of the situation right off the bat.
Most fire alarms have the segment location of the alarm showing on the screen. There are 2 buttons on the panel, one of which is used to acknowledge the alarm and automatically notify the fire department via a phone line attached to the computer. Don't worry, the other button is used to silence the alarm in case of a false alarm.
The fire alarm annunciator also conveys other types of information, like the working status of the fire alarm devices, as well as the sprinkler system. These are represented by LED lights and data which vary from model to model. Fire alarm annunciators can malfunction for a variety of reasons though. So, keeping the fire alarm annunciators in good working order is vital for the health of the entire fire alarm system.