Microchips are small identification devices implanted under your pets skin between their shoulder blades (usually).  They are about the size of a grain of rice, and have serial numbers encoded that can be read by microchip scanners.  Most veterinarians and animal control agencies have these scanners, so when a dog or cat is found and brought into the facility, they are able to read the number and contact the owner.
Numerous brands of microchips exist, but they all work the same way.  We use Home Again, which provides additional perks to their clients’ pets.  Along with the pet’s information being kept in their database for life, they offer optional additional services at a small cost.  For an additional $19.99 per year, your pet can be enrolled in their “perks program”.  This includes a Found Pet Travel Assistance that includes up to $500.00 in travel assistance to get the pet returned home if the pet has traveled over 500 miles away.  Additional perks include: 24/7 Emergency Medical Hotline($65 value per call), which is a free anytime telephone assistance provided by licensed ASPCA veterinarians, and the ability to make lost posters on their website.  Lastly, if your pet is missing and you notify Home Again, they will contact all of the local vet offices and animal control agencies near your home to let them know to keep an eye out for your pet.

The normal costs for these services include:
Microchip with implant fee: $46
This cost includes the microchip, the cost to implant, the activation fee, and 1 year of the “perks program”.
This photo shows a microchip.  It is only 1/2 inch long.