Affinity mapping is a foundational qualitative research method used to organize large volumes of unstructured data, such as interview responses, open-ended survey answers, or observational notes, into meaningful thematic groupings. Researchers sort individual data points by similarity, allowing patterns to emerge from the bottom up rather than being imposed top-down. In consumer and market insights work, affinity mapping bridges the gap between raw participant language and the structured findings that stakeholders can act on. It is especially valuable after in-depth interviews or focus groups, where the volume and richness of responses can otherwise overwhelm analysis. When applied rigorously, affinity mapping surfaces the themes, tensions, and priorities that drive real customer behavior.