Smoke alarms save lives. If there is a fire in your home, smoke spreads fast and you need smoke alarms to give you time to get out. Having a working smoke alarm cuts the chances of dying in a reported fire in half. Almost two-thirds of home fire deaths resulted from fires in homes with no smoke alarms or no working smoke alarms.
This NFPA video provides the latest information on types of smoke alarms you need, their placement and special features. Working smoke alarms give you early warning to help you escape a fire.