SaaS and Recurring-Revenue Metrics
Subscription businesses changed what "revenue" means. When customers pay every month instead of once, a whole new vocabulary appears — MRR, ARR, churn, net revenue retention, the Rule of 40 — and these metrics, not the raw P&L, are how SaaS companies are actually judged. For any engineer working at or evaluating a subscription business (which is most software today), these are the numbers that matter, and the logic behind them explains why SaaS companies behave the way they do.
Subscription businesses changed what 'revenue' means. When customers pay every month instead of once, a whole new vocabulary appears — MRR, ARR, churn, net revenue retention, the Rule of 40 — and these metrics, not the raw P&L, are how SaaS companies are actually judged.