The Itemwiki alias Itemlist ist a menu, where you can look up every Item from the Server. It tells you the Name, Element and level.
If you hover over the Item and its a kind of Box or Chest you can view its belonings with the Key STRG.
You can also Specifiy Items you want to pickup (with your Buffpet or Pick-Up Pet) have a look on the Petfilter.
You can find the Itemlist in the Menu -> Helper or Hotkey SHIFT + I