Augmented Reality is merging the real world with the digital one.When you look to a building, you will see an additional information about that building like the history of it or how did it look in the past.it can be Text, Image, Video, 3D model, etc.

Augmented Reality (AR)  VS
Virtual Reality (VR):

Some People mix between this two two terms.
The difference between Augmented Reality (AR) & Virtual Reality (VR). That Virtual Reality is only digital and it does not blend with the real world.
Virtual Reality takes you to another digital world. You can use sensors from the real world to detect body movement to make the experience more realistic & enthusiastic. What you will see will be full digital experience.
Example (VR): Simulating a crush or disaster scene to paramedics for practicing purposes.