Circular motion

How do you explain why a car skids of the road when it travels at high speed at a curve or roundabout in an a level physics explanation and what does banking do?

What do you think would happen if the road was perfectly smooth and you attempted to turn?

It would be hard to turn as there is no friction

Yes, and without friction the tyres would not be able to apply force in the opposite direction to that of motion and the back end of your vehicle would slip, causing sliding. The coefficient of friction determines the friction force given a particular road surface material. A rough surface will have a higher coefficient of friction as there will be a higher overall frictional force when the tyres exert force on the road surface. When the frictional force is exceeded, that causes skidding as the tyres slip due to the unbalanced forces. This turning force is what is known as torque.

I understand that but our physics teacher was mentioning something about limiting velocity to do with this how does that relate to this