A car alarm is a security device installed in vehicles to deter theft and unauthorized access. It typically consists of sensors that detect movement, door openings, or glass breakage. When triggered, the alarm emits a loud sound to alert the owner and nearby individuals. Most car alarms also include a remote control for the owner to activate or deactivate the system. Some advanced models may feature additional functions, such as GPS tracking or smartphone notifications. Overall, car alarms serve as an important tool in protecting vehicles from theft and vandalism.