Oh my ... Sir Postalot will post the entire Internet related to cats in this thread ...
That's a good idea.I let my cat run around in the yard, but I put a leash on him and let it drag behind him. It gives him some freedom to run, but also allows me to catch him more easily if he starts to head somewhere I don't allow him to go. I live almost right against a busy road(US-41). Otherwise, I'd let him run free.
Sam loves his toys
Im not sure if you need a harness (like on that pic) or if you can use a regular collar to use a leash on a cat.