This document discusses key startup metrics for evaluating the performance and health of a startup business. It introduces metrics related to customer acquisition cost (CAC), lifetime value (LTV), average revenue per user (ARPU), gross margin, churn rate, burn rate, and how these metrics can be used to determine if a startup will be profitable with a CAC lower than the LTV. Formulas are provided for calculating various metrics like CAC, LTV, and examples are given to demonstrate how metrics can indicate whether a startup business model is viable or not.