The document discusses three main theories of retail development: 1. Environmental theory attributes changes in retail to changes in the environment retailers operate in, such as customers, competitors, and technology. According to this theory, retailers must adapt to environmental changes or risk decline. 2. Cyclical theory, such as the Wheel of Retailing theory, suggests retail changes follow identifiable phases as innovators offer low prices but then "trade up" as they become established. 3. Conflict theory posits that conflict between similar retailer formats leads to the development of new formats, as retail evolves through a blending of opposites.