What it means
Popularised by Amazon and Jim Collins, the flywheel replaces the leaky funnel as a mental model. Lower prices attract more customers, which attracts more sellers, which lowers prices further. Each turn requires less push because the accumulated mass keeps it spinning.
Why it matters
It reframes strategy from "where do we pour effort" to "what compounds." For a marketing engine, the flywheel is usually: great work produces results, results become proof (case studies, reviews, word of mouth), proof lowers acquisition cost, which funds more great work. Identify your flywheel and remove friction from each stage.