This may not be news to you, but it is to me - and how brilliant it is! It's possible to track your cat in case he/she wanders off somewhere. Some cats are gone for weeks, or even longer and you're out there day and night desperately searching for him/her.
In the US you can have a little chip put in under the skin and you can track your cat just like with a GPS. Isn't that smart!
There are lots of links here that explain: