What it means
Lifecycle stage is the standard CRM concept of where each contact sits in the journey from stranger to customer to advocate. The most common stages: Subscriber (signed up for content), Lead (engaged but unqualified), Marketing Qualified Lead (MQL), Sales Qualified Lead (SQL), Opportunity (in active deal), Customer, Evangelist (refers others).
Different CRMs use different exact stage names but the underlying concept is universal. Stages move in one direction normally (forward) and sometimes go backward (a customer churns).
Why it matters
Lifecycle stage is the cleanest way to slice your contact base for any business decision: who to broadcast to, who to call, who to retarget on ads, who to suppress from acquisition campaigns. Without it, all contacts look the same.
Reporting also depends on it. 'Cost per Lead' is misleading. 'Cost per Marketing Qualified Lead' or 'Cost per Sales Qualified Lead' is what actually correlates with revenue.
Example
An insurance broker runs a Meta ads acquisition campaign. The cost per Lead is SGD 12 (everyone who messaged on WhatsApp). The cost per MQL is SGD 28 (responded to qualifying questions). The cost per SQL is SGD 65 (committed to a callback). The latter two are the numbers the team optimises against, not the headline cost per Lead.