Flashers, relays, and circuit breakers are types of electrical switches.
Flashers. Flashers are what cause turn signals and hazard lights to blink or flash. Flashers are classified into three types: thermal/bimetal, hybrid, and solid state/electronic.
Relays. Relays allow a small current to control a circuit requiring a high current.
Circuit Breakers. Circuit breakers are used to protect overloaded circuits. Unlike fuses that blowout, circuit breakers reset automatically after they have cooled. Headlights and other high current components may be on circuit breakers.