The Map of Eterra (bound to M by default) provides lots of useful information about the world. You can find important story locations, keep track of your campaign progression, use waypoints to travel between different areas and Eras, and see how time and the Void has shaped the world from what it once was.
At the top of the World Map UI, you can see a timeline with four different periods of time, or Eras. Through your travels in Eterra you visit these different Eras many times, and by clicking at any of them you can see the what Eterra looks like in different Eras throughout its history.
On the left side of the World Map, you have a quest log that consists of your current active main and side quests, completed quests and the ability to pin or unpin quests that are then shown on the right side of your UI while you are playing.
Clicking on a quest will bring a more detailed quest information and changes the Era of your UI and show where and when that quest is located at.
Main quests are displayed with golden color, while side quests are in silver.
You can also hover on a specific area or Era that has quest icons to see the names of those quests, and by right-clicking on an area with a unlocked waypoint you can immediately travel there from anywhere.
At the bottom left corner you can see how many of the maximum unlockable passive point and idol slot quest rewards you have obtained from completing quests. There are much more quests providing these rewards than the maximum, so you can choose to complete different quests while being able to get the maximum passive point and idol slot rewards.