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

• 2 interface for 5V Servo connected to For Arduino's high-resolution dedicated timer - no jitter.
• Can drive 4 DC motors or 2 stepper motors or 2 Servo.
• Up to 4 bi-directional DC motors with individual 8-bit speed selection
• Up to 2 stepper motors (unipolar or bipolar) with single coil, double coil or interleaved stepping.
• 4 H-Bridges: per bridge provides 0.6A (1.2A peak current) with thermal protection, can run motors on 4.5V to 16V DC

- Pull down resistors keep motors disabled during power-up

- reset button

- 2 external terminal power interface, for seperate logic/motor supplies

- Tested compatible for Aduino Mega, Diecimila & Duemilanove