Traffic segmentation is the division of visitors into groups that behave differently. Without it, you work with an average that mixes together a first-time visitor from an ad and a returning customer, mobile and desktop, the domestic and foreign market. The resulting average then describes no one and conceals significant problems. Meaningful segments are those where you can intervene differently: by traffic source, device, visitor novelty, region, landing page, or purchase stage. Within them, compare conversion rate, order value and the path taken on the website. The most common discovery is that mobile conversion lags so much that it drags the overall figure down, even though mobile accounts for the majority of visits. Define segments once and use the same ones across reports, so that results can be compared between periods and between teams.
See also: Cohort analysis, Mobile usability, Data quality in analytics.
