Most cats won’t keep collars on for long. A microchip is a small computer chip (about the size of a grain of rice) that holds only a number. This number links your cat to you should he get lost. When a scanner is held over the chip, the number can be read on the screen. Getting lost used to mean that cats were usually not reunited with their owners. Microchips (radio frequency identification device RFID) changed that. The chip is injected with a special device under the skin. You register its unique ID number on a website with contact information. The link is now set between you and your cat. Fire season taught us that indoor cats should be microchipped, too.