What is augmented reality?
Augmented reality is where what you are viewing on a computer device (computer, tablet, phone, etc) is pictures or video of the real world around you, but there is additional stuff in it that is not real.
PokemonGo is an example of augmented reality. It uses the camera on your phone to give real video of the surroundings you are in, so it is live video. However it is augmented reality because it adds the Pokemon characters in to the real images and if you were to look away from your screen you would think you could actually grab them, but they have been virtually added to the picture.
PokemonGo shows the new level of augmented reality, to mix reality (the real world) and virtual reality which has the imaginary characters.
This is not the first use of augmented reality. People that watch football games and baseball games on TV have seen augmented reality and are sometimes surprised when they actually go and watch a game and find some things are not real. For instance in football it continuously shows us a bright line across the field, which is the first down line. That is added at the TV studio and is not really there.
In baseball there are ads continuously appearing on the wall behind home plate and you go watch a game in person and discover it is a plain wall. Both cases are using augmented reality.