A microchip is a device that is the size of a grain of rice and contains a digital personal identification number. The chip is implanted under the skin, usually between the shoulder blades, using a needle. The number is registered with a service that is available by phone 24 hours a day. If the pet is found, a scanner is used to obtain the number and the owner is called. Most humane organizations, veterinarians, animal emergency clinics, dog pounds and animal rescue organization have scanners.