Market segmentation involves dividing a market into groups of customers with distinct needs and behaviors who may require separate products or marketing mixes. The document discusses the 5 steps of market segmentation: 1) grouping potential buyers into segments based on characteristics, 2) grouping products into categories, 3) developing a market-product grid to estimate segment sizes, 4) selecting target segments based on criteria like size and costs, and 5) taking marketing action such as with pricing, advertising, and promotions to effectively reach the target segments. Segmentation allows companies to better satisfy customer needs and increase profits by developing tailored marketing strategies for different consumer groups.