The main purpose of a smoke detector is to provide early warning of fire by detecting smoke or heat in the environment. When smoke particles enter the detector, they disrupt a light beam or ionization process inside, triggering an alarm to alert occupants of potential danger. This timely alert allows people to evacuate and seek safety before a fire spreads. Smoke detectors are crucial in residential homes, commercial buildings, and public spaces, significantly increasing the chance of survival during a fire incident. Regular maintenance, including battery replacement and testing, is essential to ensure their effectiveness.