A stock-keeping unit or SKU is a unique identifier for each distinct product and service that can be purchased. It helps the company to systematically track its inventory or product availability, such as in warehouses and retail outlets. Hence “these units are stock at a specified location taking into account the transport and purchasing costs”. 1) Every SKU is assigned a unique identification number for transparency purposes.
Each SKU is attached to an item, variant, product line, bundle, service, fee, or attachment. Successful inventory management systems assign a unique SKU for each product and also for its variants, such as different versions or models. This allows merchants to track and compare sales figures in order to e.g. identify weak, low volume and unprofitable products.
Demand forecasts can effectively be done at the SKU level: http://www.prtm.com/StrategicCategory.aspx?id=4027&langtype=1033