From April 2016 it became a legal requirement for all dogs to be microchipped in England.

A microchip can help ensure your pets safe return if he/she gets lost. If your pet strays and is injured it can help ensure you are contacted as soon as possible by the treating vet. 

A microchip is about the size of a grain of rice and is injected under the skin between the shoulder blades. The microchip carries a unique identification number, once this has been registered all your details will be held on a national computer database which you can update as required.

A microchip has the advantage over a collar and tag as it is not easily lost. However, it is a good idea for your pet to also have a collar and tag, showing your name and phone number.  For cats this should be a quick release type to prevent accidental injuries.