A microchip is a small, electronic chip enclosed in a glass cylinder that is about the same size as a grain of rice that is injected under your pets skin using a hypodermic needle.  It is no more painful than a typical injection although the needle is slightly larger.  No surgery or anesthesia is required and the chip can be inserted during a routine veterinary visit.  However, a great time to have your pet microchipped is when they are already undergoing an anesthetic procedure such as spaying or neutering. Microchips currently contain identification numbers that link to a database where you will have registered your information.  They are not GPS trackers, however if your lost pet is found by a good samaritan and taken to a veterinarian or a shelter, they will be scanned and you can be reunited with your pet.