Ability bar
Ability bar is the most important part of the user interface as it's not only showing important informations, it's also the only way to use spells.

Hitpoints and mana
These bars at the top of the ability bar show your current hitpoints or mana out of your maximum hitpoints / mana.
The hitpoints bar also shows your shield's hitpoints (if you have any active) as a smaller blue bar. The hitpoints numbers also change to blue.

Spell slots
The ability bar always has a visible set of 10 slots for spells or consumables and additional set of 10 invisible slots. You can swap between these by pressing the "Swap ability bars" key (Tab by default). When you do so, the keybinds stay the same for both sets.
You can drag spells or consumables to these slots and use them by pressing the keybind or clicking them (although since you need your mouse to target many active spells, this might be useful mostly for consumables or instant spells).
You also have additional 20 slots on the side. These slots are by default visible only if you're dragging spells or consumables or if you toggle them in settings.

Cooldowns and amounts
Slots also show the cooldown of the spell or consumable inside of them along with charges (for spells like Teleport) or amount for consumables. This amount is based on how many of these items do you have in the entire inventory. When you use a consumable this way, it automatically removes it from the emptiest stack in your inventory.
Status effects
Short term status effects
You can see all buffs currently affecting you above the hitpoints bar and all active debuffs above your mana bar.

Long term status effects
These status effects are shown on the left side from your ability bar and they show all of your active long term consumable effects (utility potions, combat potions, food and elemental essences).

Buttons part
Ability bar also has a few buttons you can use to open some other windows.

Top row:
- Inventory button
- Character window button
- Skills window button
- Journal button
- Map button
Middle row:
Bottom row