Not only can each category be sub-divided but there is also considerable overlap between categories. Take, as an example, retail and warehouses. Retail properties come in various forms. The obvious example is a shop in a street, but even there they vary from kiosks to standard shop units to departmental stores. Over recent years there has been extensive development of shopping centres where the shopper enters off the shopping street into a development of various retail units under one roof, frequently with its own multi-storey car park. A further development has been the creation of edge-of-town centres where the shopping centre is surrounded by extensive car parking. A yet further trend has been the development of out-of-town stores of large size, generally food based, again with extensive car parking, described as superstores. In the non-food sector there has been the creation of one-off or groups of retail parks, selling furniture,
DIY or carpets, each of a size larger than the traditional shop units, with extensive car parking as a key element. These are often referred to as retail warehouses, to distinguish them from the traditional distribution warehouse where goods (wares) are housed in bulk prior to distribution to other smaller traders or retail outlets.