1) The document discusses key metrics that matter for startups and businesses, including actionable metrics, customer acquisition cost (CAC), lifetime value (LTV), and cohort analysis.
2) It defines CAC as the cost of acquiring a new customer divided by the number of customers acquired, and notes mistakes like failing to include all acquisition costs.
3) LTV is defined as the predicted net profit from the future relationship with a customer.
4) Cohort analysis breaks users into groups based on acquisition date to analyze engagement over time. This provides insight into how the business and product are evolving.