Cohort analysis is the practice of grouping users by a shared characteristic and tracking their behavior over time as a group. The shared characteristic is most often acquisition date, but also acquisition channel, plan tier, geography, or onboarding path. It is used to surface trends and inflection points that blended averages hide, and is the standard methodology underneath retention measurement, LTV calculations, and most credible product-market-fit assessments.
The canonical cohort chart is a triangle: rows are cohorts (e.g., users who signed up each week or month), columns are time periods since signup (Day 1, Day 7, Day 30, Month 3, Month 12), and each cell shows what percentage of that cohort was still active or payin...