The L293D is a monolithic integrated, high voltage, high current, 4-channel driver. This means that by using this chip you can use DC motors and power supplies up to 36 Volts, which means some pretty big motors, and the chip can supply a maximum current of 600mA per channel. The L293D chip is also known as an H-Bridge type. The H-Bridge is typically an electrical circuit that allows the voltage to be applied to a load in any direction towards an output, e.g., a motor.