​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.
 
FAQs

• Microchips contain no GPS and do not transmit a signal unless a scanner is in use. They cannot locate your cat (or you). They only contain a unique number that can be linked to you and your cat if you provide the information to do so to the company who produces the microchips. 
  
• A universal scanner is owner by most veterinarians, shelters, humane organizations, and some pet stores. Any animal found by any person can go to any of these places and get the RFID number from the chip to help rejoin the cat and owner.
  
• Your microchip will never “expire” once it is in place. There are companies that sell subscriptions in addition to microchips that provide extra help should your cat get lost. These subscriptions do expire and are also not necessary to purchase.
  
• Any time you move, get a new phone number or change any other contact information, you can call the toll free number for the microchip company  and provide an update. The information is kept on secure servers, making it safer than appearing on a collar tag.
  
• Cats as young as 6 weeks can be microchipped as long as they are healthy and normal size. Placement is largely painless and is often done under anesthesia during routine kitten surgeries.
  
• Indoor cats should always be microchipped.  Emergency evacuation, someone inadvertently leaving a door ajar,  a sudden noise that causes a cat to flee are a few of the many reasons why indoor cats get lost.
  
• Microchips do not cause cancer.  Rumors of this came from studies of cancer in laboratory rats and mice. Two cats have been reported with cancer near a microchip and only one could be associated with it. The risk that your animal will develop cancer due to its microchip is very, very low, and is far outweighed by the improved likelihood that you will get your cat back if he becomes lost.
  
• Cats who are microchipped are thought by the person who found them  as being “owned” by a human. This means they will likely put some effort into helping you be reunited rather than being dropped off at a shelter and thought of  as a stray.
  
• Microchips must be read by a scanner. Some older scanners could only read numbers belonging to their company’s microchips. There are universal scanners which can read all of the signals now. The sequence of numbers will identify the company to contact. Only one phone call is required to the company that sold the microchip.
  
• Some cats can look very similar. Checking multiple shelters for your beloved cat is stressful. Mistakes can be made. Having a microchip identifies you as the owner of this cat. No one else can claim him.
  
• Cats are very territorial and cats that routinely go outside may be able to find their way home. But fear and stress can interfere with memories of location. Cats CAN get lost.