Market segmentation involves dividing the total market into groups of customers with similar needs and wants. This allows retailers to customize their products, services, and promotional campaigns for each segment. Effective segmentation criteria includes segments that are homogeneous within themselves but heterogeneous from each other, substantial in size, actionable to identify customers, accessible to target, and measurable. Segmentation helps retailers with development of marketing mix, store location decisions, understanding customer behavior, merchandising decisions, and promotional campaigns.