A 12V adapter is a power supply unit that converts household AC voltage (100V-240V) into a stable 12V DC output, widely used for electronics like LED strips, routers, and security cameras. They typically feature a 2.1mm x 5.5mm DC plug and come in various amperage ratings (e.g., 1A, 2A, 6A). Safety features often include overvoltage, overheating, and short-circuit protection.