Data saturation is a foundational concept in qualitative research methodology, referring to the stage at which new participant interviews no longer surface meaningfully distinct themes, behaviors, or perspectives. At this point, the researcher has collected enough depth to draw credible, defensible conclusions from the data. Reaching data saturation is widely accepted as a marker of rigor in qualitative studies, including in-depth interviews, focus groups, and ethnographic research. The number of interviews required to reach saturation varies by research question, participant diversity, and topic complexity, but most practitioners find it occurs somewhere between 12 and 30 interviews in a well-scoped qualitative study.