Actually the technology is called AUGMENTED REALITY.
Pokémon Go uses your phone’s GPS and clock to detect where and when you are in the game and make Pokémon “appear” around you (on your phone screen) so you can go and catch them. As you move around, different and more types of Pokémon will appear depending on where you are and what time it is. The idea is to encourage you to travel around the real world to catch Pokémon in the game(This combination of a game and the real world interacting is known as “augmented reality.”)
EXPLAIN : http://www.vox.com/2016/7/11/12129162/pokemon-go-android-ios-game