canon - What is the difference between AI Focus and AI Servo autofocus modes?

Recently I bought a Canon 60D and I am uncertain about when and how to use/activate the AI Focus and AI Servo functions.

I understand the One Shot autofocus function for still subjects. You press the shutter and the camera/lens will autofocus for you.

With AI Servo AF (for moving subjects), I also press down the shutter button and follow/point towards the subject as it moves around? Till the camera finally finds the autofocus point?

Can someone please explain if this is the correct method?

AI Servo function... I have read the menu, but I am still unsure what this does and when should I use this function.

Lastly, what is the difference of these functions when compared to “panning.”