Showcase of the inventory. There's a few things that can be done here: Getting information on items, using them and binding them to the spinjump key for use outside of the inventory.
When using a favourite'd item which you have multiple of, the favourite tag will automatically switch to the next item of the same type. That way you can use a lot of powerups without having to re-open the inventory all the time!
Items with a red backdrop are quest items and can be added to your inventory even if it's full.
More inventory spots can be bought at the shop.