Fitts’ law – ‘the science of the obvious’

Fitts’ law is about size and distance. The bigger and closer something is the easier is it to reach or in terms of screen design the easier it will be to click, whereas if it is smaller and further away it will be more difficult.

For example, when designing a form your primary action should be bigger and nearer, whereas something that you don’t want the users to click easily such as an undo or delete button (which could have catastrophic consequences) you make smaller and harder to reach.

If you want to know more listen to Jared Spool’s podcast at:
http://www.uie.com/brainsparks/2008/02/28/usability-tools-podcast-applying-fittss-law/