Churn Rate
The percentage of customers (or revenue) you lose in a period. The silent killer of recurring businesses.
How it's calculated
Churn = customers lost ÷ customers at start of period
Why it matters
Low churn lets growth compound; high churn means you're refilling a leaky bucket.
Related terms
Growth Rate
How fast a metric (revenue, users) increases period over period, usually monthly.
Activation
The moment a new user first experiences real value (their 'aha'). Not just signing up — actually getting the point.
Retention
The share of users who keep coming back over time. Often shown as a curve that should flatten (not hit zero).