Items can be categorized by their function. At the beginning, new players can only create raw materials, which are primarily used to craft commercial items. Popping chat bubbles in your town or others' has a chance to get expansion items, which is used to expand either land or storage depending on the item. Commercial items are then produced after unlocking commercial buildings. Building the airport will unlock access to specialized items used for upgrading residential houses of that type (Parisian, Tokyo, or London). Lastly, building the Vu Tower unlocks special items used for starting disasters.