Product-market fit is the point at which a product satisfies strong market demand well enough that growth becomes meaningfully easier and more organic.
PMF is famously hard to define precisely, but it's easier to recognize its absence: if a team is grinding hard on acquisition and retention with modest results despite good execution, that's often a signal the underlying product-market fit isn't there yet, and no amount of marketing optimization will fully fix it. Growth tactics generally amplify what's already working. They rarely create fit that doesn't exist.
Sean Ellis's PMF survey (asking users "how would you feel if you could no longer use this product," with 40%+ saying "very disappointed" as a rough signal) is one commonly cited, if imperfect, way teams try to measure this qualitatively.
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