The “sales funnel” or “product funnel” is a central element of online marketing (or any wise marketing, for that matter. Grocery store “loss leaders” are an example from offline marketing.). You attract interest by offering a free (or, occasionally, low-priced) product. Then you offer additional products to those who accept your initial offer. The are called “funnels” because they are wide at the beginning and grow narrow as they go on. That is, many people accept the initial offer, and as additional offers come, with prices growing ever higher, fewer... [...]