My dogs are all microchipped. When we are out and about, they wear collars with tags also. Their tags say their names, our address, cell phone number, and our first initial and last name. On the back of a couple of their tags, it says their microchip ID number. At home, none of them wear collars for safety reasons. My old trainer used to tattoo dogs and swears by it but I'm not a big fan. THE main reason being that if you ask the average person who they would call if they found a dog with a tattoo, almost no one knows.....hence making them pretty useless. And beyond that, I think they look kind of ugly on the dog and they tend to fade and are tough to read after a little while. With a microchip and tags, you just can't go wrong!