A hub system is a very busy system in EVE where a lot of pilots come together to fly missions, sell, buy and produce, thus a broad variety of items can be found in a hub system. Minerals fetch better prices in hub systems than in most other places because people like to produce right where the customers are, in order to get rid of the hassle of hauling items. Hub systems are often the cause of lag in the game because of the sheer number of pilots in one place at one time.