Most fatal fires occur at night when people are sleeping. A working smoke alarm will detect smoke and sound to alert you.
In Ontario, it's the law for all homes to have a working smoke alarm on every storey and outside all sleeping areas. This covers single family, semi-detached and town homes, whether owner-occupied or rented.
Learn more about smoke alarms, including how to install and maintain them, by vising the Ontario Association of Fire Chief's smoke alarm information page.