Market segmentation involves dividing broad target markets into specific consumer groups. There are 5 essential criteria for viable market segments: 1) They must be measurable in terms of size. 2) Be a substantial homogeneous group that will not quickly change. 3) Be accessible via appropriate marketing approaches. 4) Be internally similar but externally different from other segments. 5) Provide actionable data to inform marketing positions and sales approaches that can be quantified. Proper market segmentation allows for an efficient targeted approach to customers.