The term "Item" in Dual Universe broadly refers to any object that can be carried by a character or placed in a container. For example, iron ore (which is a resource) and an engine (which is an element), are all also considered to be items because players can carry them in their personal inventory. Constructs, on the other hand, are not items because players cannot carry assembled constructs in their personal inventory. Quanta is also not an item, because all quanta is digitally stored in the wallets of characters and organizations, and is not accessible by any other character.
The most significant difference between the item system in Dual Universe and that of many other games is that in DU all items have a physical volume. As a result, all items must be stored in a physical location at all times, such as a container, nanopack or market container. Items must also be transported (i.e. from one planet or base to another) and exchanged (i.e. bought, sold, or traded) manually.
The Item tree can be viewed fully in the market UI [j] and all player crafted items in the crafting UI [k]

Item Tree
Consumables[]
Ammunition[]
Scrap[]
Warp Cell[]
Data Item[]
Schematics[]
Elements[]
Combat & Defense Elements[]
Furniture & Appliances[]
Industry & Infrastructure Elements[]
Planet Elements[]
Systems[]
Transportation Elements[]
Materials[]
Fuels[]
Honeycomb Materials[]
Minable Materials[]
Refined Materials[]
Parts[]
Complex Parts[]
Exceptional Parts[]
Functional Parts[]
Intermediary Parts[]
Structural Parts[]