A marketing funnel is the staged model of how a person moves from first awareness of a product to a paying, retained, and referring customer. It is used to organize marketing tactics and performance metrics by stage rather than by channel. It is a diagnostic frame for finding where customers drop off, not a literal description of how any individual customer thinks.
Classic funnels work top to bottom: Awareness, Consideration, Conversion, Retention, Advocacy (a modernized version of AIDA, Awareness, Interest, Desire, Action, from 1898). Tech-flavored variants include AARRR / Pirate Metrics (Acquisition, Activation, Retention, Referral, Revenue) and Reforge's loop-oriented variant. The reason there are multiple frames is that...