UK registration numbers on cars

[Steve Reilly <Luckyone@sympatico.ca>]

List, 

  For the past 3 months that I have received magazines from the Triumph
Sports Six Club, I have noticed that they always refer to a car by its
registration, listed on the license plate. 
  Exactly what significance or what information can be gathered by knowing
the plate number?  Is the plate passed down with the car from owner-to-owner?

Thanks,
Steve Reilly
'70 GT6+