tuan, the chip is not like a gps device. it only stores information. for example, say your dog gets loose from the back yard and runs amuck... well if someone finds him, they can call animal control or take him/her to the local shelter... they can scan the chip to get your contact information and you can come pick the dog up... if its a freak situation and the dog's really far away like maybe someone stole it and it turned up in a shelter somewhere, i've heard of them shipping the dog back to you.