Inventory
Inventory is a part of your user interface where you can see all items you collect. It starts with 32 slots but can be expanded until up to 72 slots with inventory expanders.

Using the inventory
You can drag and drop items from one slot to another. If this slot is already taken, these items will swap positions.
Filters
You can activate a filter for a group of items by clicking the filter button

or by entering the item's name into the search bar.

After doing so, only the items you were looking for will be well visible.

Sorting
You can also sort items by clicking the sort button. Doing so will completely rearange your inventory.

Stacking
Equipment is the only item type which cannot be stacked. You can stack the rest by simply dragging an item on top of the same item. Each item can be stacked up to 99 times in a single inventory slot.
Context menu opens by right clicking an item. The options are based on what other windows do you have opened and the item you're opening it on.

- Equip (equipment only) - Equips this item. If you already have something equipped in this slot, you will swap these items instead.
- Use (consumables only) - Uses this item - drinks a potion, learns a recipe, uses an inventory expander, etc.
- Throw away - Throws away this item
- Split (stackable items only) - Splits this item into 2 equally large stacks
- Sell (while trading only) - Sells this item
Using an item this way doesn't necessarily remove it from the stack you right click on but it automatically removes it from the lowest stack of this item in your inventory.
Discarding items
You can throw items away if you don't need them and you want to quickly make space in your inventory. You can do this by simply dragging it to the left side of the inventory.

You can also throw it away from the context menu.
This option is however disabled if you're trading as there's no reason to not simply sell the item instead. Items that cannot be sold also cannot be thrown away.
You cannot recover items you throw away.