You need Knowledge Points to progress through the game. They are stored in the bar at the top of your game screen:
You receive 1 Knowledge Point per hour, up to a fixed maximum of 10 (can be temporarily raised to 20 using Enchantments), and additional Knowledge Points can be purchased using Coins or Diamonds. Additionally, you can get Knowledge Points by solving encounters on the World Map or while playing the Tournaments. They can be used for research and can be donated to the Ancient Wonders of other players or to your own.