▁hier arch ical ▁system , ▁such ▁as ▁A ID A , ▁provides ▁the ▁mark eter ▁with ▁a ▁detailed ▁understanding ▁of ▁how ▁target ▁aud ien ces ▁change ▁over ▁time , ▁and ▁provides ▁ins ights ▁as ▁to ▁which ▁types ▁of ▁advert ising ▁messages ▁are ▁likely ▁to ▁be ▁more ▁effective ▁at ▁different ▁jun ct ures . ▁Mov ing ▁from ▁step ▁to ▁step , ▁the ▁total ▁number ▁of ▁prospect s ▁dimin ishes . ▁This ▁phenomen on ▁is ▁sometimes ▁described ▁as ▁a ▁" p urchase ▁fun nel ". ▁ ▁A ▁relatively ▁large ▁number ▁of ▁ ▁potential ▁purch as ers ▁become ▁aware ▁of ▁a ▁product ▁or ▁brand , ▁then ▁a ▁smaller ▁subset ▁becomes ▁interested , ▁with ▁only ▁a ▁relatively ▁small ▁proportion ▁moving ▁through ▁to ▁the ▁actual ▁purchase . ▁This ▁effect ▁is ▁also ▁known ▁as ▁a ▁ ▁" customer ▁fun nel ", ▁" mark eting ▁fun nel ", ▁or ▁" s ales ▁fun nel ". ▁ ▁The ▁model ▁is ▁also ▁used ▁extens ively ▁in ▁s elling ▁and ▁advert ising . ▁According ▁to ▁the ▁original ▁model , ▁" the ▁steps ▁to ▁be ▁taken ▁by ▁the ▁s eller ▁at ▁each ▁stage ▁are ▁as ▁follows : ▁ <0x09> <0x09> ▁ ▁Stage ▁I . ▁Sec ure ▁attention . ▁▁ <0x09> ▁ ▁Stage ▁II . ▁Hold ▁attention ▁Through ▁Interest . ▁▁▁ <0x09> ▁ ▁Stage ▁III . ▁Ar ouse ▁Des ire . ▁▁ ▁Stage ▁IV . ▁Create ▁Conf idence ▁and ▁Bel ief . ▁▁ ▁Stage ▁V . ▁Sec ure ▁Dec ision ▁and ▁Action . ▁▁ ▁Stage ▁VI . ▁Create ▁Sat isf action ." ▁ ▁Crit ic