Product-market fit
Product–market fit is the point where enough of a focused segment would be genuinely disappointed to lose your product — Sean Ellis's 40% test is a common proxy, backed by a retention curve that flattens rather than decaying to zero. For early-stage teams it is often the outcome at the root of their discovery tree.
Related terms
Assumption
A belief a solution depends on. If it turns out to be wrong, the solution fails — so the risky ones are worth testing first.
Assumption mapping
Plotting each assumption by importance and evidence to find which to test first — the high-importance, low-evidence ones.
Continuous discovery
The habit of weekly customer contact feeding product decisions, rather than a one-off research phase before a project.
Customer interview
A story-based conversation that uncovers real needs — you ask about specific past moments, not hypotheticals or opinions.
North star metric
The single metric that best captures the value customers get from your product, used to align the whole team.
Opportunity
A customer need, pain, or desire — phrased as a problem (“I can’t tell which teams are active”), never as a solution.