A collar and tag will only go so far. A collar or tag can easily fall off or be removed. A microchip isn’t going anywhere. Microchipping substantially increases the likelihood of a pet returning home when it is lost.
Once your pet is microchipped you should make sure the microchip is registered and keep your registration information up-to-date. If you have moved, or if any of your information (especially your phone number) has changed, make sure you update your microchip registration in the manufacturer’s database as soon as possible. We routinely microchip your pet during their first set of vaccines but this procedure can be for adults too.