Market segmentation refers to dividing a market into subgroups of customers with distinct needs and characteristics that lead to similar responses to marketing efforts. It allows companies to target specific segments effectively. There are three main criteria for segmentation: homogeneity within segments, distinction between segments, and similar response to the market. Effective segmentation creates identifiable, accessible, profitable, and durable segments that meet unique customer needs and can be measured. It facilitates choosing marketing targets and developing tailored and efficient marketing strategies for each segment.