motors (and or motor shield)

So with the adafruit motor shield, do you need external power for the motors. What I can glean from reading around it seems motors draw more than the arduino can supply. So at most it can supply the power to switch when the motors are on and off but not the juice to run the motors itself? Am I correct at this? The motorshield seems to have an extra plug for juice, this to help power motors?

-Shane

Am I correct at this?

Depends on the motor but in general terms yes. The USB socket can only be relied upon to supply 500mA and that is often too much for the switch on surge of the motor.

Yes, in general you'll need an external power supply for high-current devices. That means motors, servos, solenoids, heaters, larger sizes of light bulbs, and so on.