Market segmentation involves dividing markets into distinct segments based on characteristics like geography, demographics, behaviors, and psychographics. Effective segmentation creates segments that are measurable, accessible, substantial, differentiable, and actionable. Market targeting selects specific segments to target with tailored marketing strategies like differentiated, concentrated, or micromarketing. Positioning determines how a product is defined in consumers' minds relative to competitors based on important attributes. Choosing the right positioning strategy involves identifying competitive advantages, selecting a value proposition, and consistently communicating and delivering the chosen position through all marketing mix elements.