"Funnel" is a term of web marketing, often associated with a lot of other terms (purchase funnel, sales funnel, conversion funnel, to name only the best known), which, theoretically, is the model applicable to almost all websites, especially valid for e-commerce, the landing page, the squeeze page or other sites and pages that try to turn a visitor into a simple customer.

It is a real "funnel" where, from the top, come in the views from users, and from the bottom come out - or at least they should get out - sales and conversions.