Lets you know what crafted items a resource/item is used to make.
Start typing the name of an item/resource into the input box. As you type suggestions will be shown. When you see the item/resource you want click on it to get a list of all the crafted items it is used to make.
Clicking on an item in a 'Used In' area will show the recipe (what's used in making it), the effects this item has when equipped and a list of any items it is used in making.