1) In Aztec mythology, Quetzalcoatl is a prominent deity often depicted as a feathered serpent. He is associated with creation, fertility, and wind, and is considered a cultural hero and patron of priests and rulers. The arrival of Spanish conquistadors was interpreted by some as the return of Quetzalcoatl.

2) The concept of augmented reality (AR) involves overlaying digital information and virtual objects onto the real world, enhancing the user's perception and interaction with the environment.

3) The word "school" contains two vowels: O and O.

4) The word "piano" contains three vowels: I, A, and O.