It would be much easier for everyone if all dogs wore a tag with owner contact information.
If your dog gets lost, and someone finds it, they can make a quick phone call to the number listed on the tag. easy! Rather then to have to bring a found dog to a vet to check for a microchip, try to track down the owner through any vaccination or city tags, putting up lost & found posters all over the city, calling the pounds, shelters, all the stress and worrying, etc. It just makes sense to have your pet wear a tag.
So, for the sake of your pet, please make sure they have a tag. Try to get a sturdy one that will not break easily.
Here are some cool tags I found on etsy...
*cristina ashley design * lucky fiona * julep115 * bynicola
* windshine * a passion for fashion * sudlow * loosewirestudio