The classic: how do card readers work
returns NSC as number 1, of course, just easing out Wikipedia.
https://www.google.co.uk/search?q=how+do+card+readers+work&sourceid=ie7&rls=com.microsoft:en-gb:IE-SearchBox&ie=&oe=&gws_rd=cr&ei=rzqLUoeJG4-RhQeTuoGQDA