Dave McClure's AARRR framework breaks growth into five measurable stages:
A — ACQUISITION: How do users find you?
A — ACTIVATION: Do they have a good first experience?
R — RETENTION: Do they come back?
R — REVENUE: Do they pay you?
R — REFERRAL: Do they tell others?
Each stage is a filter. Users flow through.
Your job is to optimize each stage so more users make it through.