Main interface is rather intuitive and similar to many other MMO or RPG games (you can move its elements around when entering Rearrange HUD mode in man menu):
1: Character portrait with level, class icon, name and buffs/debuffs.
2: Companion portrait, his HP bar and experience bar.
3: Group window, each member has his portrait, class icon, level, name, health bar, voice chat icon, buffs and debuffs.
5: Minimap with current time.
6: Quests list, PvP domination status and current map event information.
9: Experience bar
10: After each new level "What's New" window will appear here with new unlocks (more in character progression) you'll also see here information about picked up Gold and loot.
11: Information about current and upcoming hourly events
12: Invocation icon allowing you to pray to your gods, next to it is Vault of Piety icon opening window that allows to trade coins from invocation, and counter showing how many Celestrial coins you collected (how many days in succession you have been praying, showing maximum 7)
13: Quick menu.
14: Boss health bar with its buffs and debuffs