1 9 8 0 s . ▁Ever ▁since , ▁according ▁to ▁Elli ott ▁( 2 0 0 4 ), ▁" the ▁traditional ▁life ▁cycle ▁approaches ▁to ▁systems ▁development ▁have ▁been ▁increasing ly ▁replaced ▁with ▁alternative ▁approaches ▁and ▁frameworks , ▁which ▁attempted ▁to ▁overcome ▁some ▁of ▁the ▁inher ent ▁def ic ien cies ▁of ▁the ▁traditional ▁SD LC ". ▁ ▁Ph ases ▁ ▁The ▁system ▁development ▁life ▁cycle ▁framework ▁provides ▁a ▁sequence ▁of ▁activities ▁for ▁system ▁design ers ▁and ▁developers ▁to ▁follow . ▁It ▁consists ▁of ▁a ▁set ▁of ▁steps ▁or ▁phases ▁in ▁which ▁each ▁phase ▁of ▁the ▁SD LC ▁uses ▁the ▁results ▁of ▁the ▁previous ▁one . ▁ ▁The ▁SD LC ▁ad her es ▁to ▁important ▁phases ▁that ▁are ▁essential ▁for ▁developers — such ▁as ▁planning , ▁analysis , ▁design , ▁and ▁implementation — and ▁are ▁explained ▁in ▁the ▁section ▁below . ▁This ▁includes ▁evaluation ▁of ▁the ▁currently ▁used ▁system , ▁information ▁gather ing , ▁feas ibility ▁studies , ▁and ▁request ▁appro val . ▁A ▁number ▁of ▁SD LC ▁models ▁have ▁been ▁created , ▁including ▁water fall , ▁f ount ain , ▁spir al , ▁build ▁and ▁fix , ▁rapid ▁pro tot yp ing , ▁increment al , ▁synchron ize , ▁and ▁stabil ize . ▁The ▁oldest ▁of ▁these , ▁and ▁the ▁best ▁known , ▁is ▁the ▁water fall ▁model , ▁a ▁sequence ▁of ▁stages ▁in ▁which ▁the ▁output ▁of ▁each ▁stage ▁becomes ▁the ▁input ▁for ▁the ▁next . ▁These ▁stages ▁can ▁be ▁character ized ▁and ▁divided ▁up ▁in ▁different ▁ways , ▁including