Stores systems involve planning for materials needs through forecasting, periodic review of forecasts, and optimizing resources to efficiently meet actual needs. Efficiency is measured by stock turnover, meaning how quickly materials move through the stores. Stores encompass a wide variety of materials that require specialized storage, handling, and licensing depending on the product. The key responsibilities of stores personnel are to properly account for all received items, preserve materials until issue, and issue materials as demanded. Effective stores management has main functions of receiving, custody, inventory control, and disposal of materials.