LC ▁models ▁or ▁method ologies ▁have ▁been ▁created , ▁such ▁as ▁water fall , ▁spir al , ▁Ag ile ▁software ▁development , ▁rapid ▁pro tot yp ing , ▁increment al , ▁and ▁synchron ize ▁and ▁stabil ize . ▁ ▁SD LC ▁can ▁be ▁described ▁along ▁a ▁spectrum ▁of ▁ag ile ▁to ▁iter ative ▁to ▁sequ ential ▁method ologies . ▁Ag ile ▁method ologies , ▁such ▁as ▁XP ▁and ▁Sc rum , ▁focus ▁on ▁light weight ▁processes ▁which ▁allow ▁for ▁rapid ▁changes ▁( without ▁necessarily ▁following ▁the ▁pattern ▁of ▁SD LC ▁approach ) ▁along ▁the ▁development ▁cycle . ▁Iter ative ▁method ologies , ▁such ▁as ▁R ational ▁Un ified ▁Process ▁and ▁dynamic ▁systems ▁development ▁method , ▁focus ▁on ▁limited ▁project ▁scope ▁and ▁expand ing ▁or ▁impro ving ▁products ▁by ▁multiple ▁iterations . ▁Se qu ential ▁or ▁big - design - up - front ▁( B DU F ) ▁models , ▁such ▁as ▁water fall , ▁focus ▁on ▁complete ▁and ▁correct ▁planning ▁to ▁guide ▁large ▁projects ▁and ▁ris ks ▁to ▁successful ▁and ▁predict able ▁results . ▁Other ▁models , ▁such ▁as ▁an am orph ic ▁development , ▁tend ▁to ▁focus ▁on ▁a ▁form ▁of ▁development ▁that ▁is ▁gu ided ▁by ▁project ▁scope ▁and ▁adapt ive ▁iterations ▁of ▁feature ▁development . ▁ ▁In ▁project ▁management ▁a ▁project ▁can ▁be ▁defined ▁both ▁with ▁a ▁project ▁life ▁cycle ▁( PL C ) ▁and ▁an ▁SD LC , ▁during ▁which ▁slightly ▁different ▁activities ▁occur . ▁According ▁to ▁Taylor ▁( 2 0 0 4 ), ▁" the ▁project ▁life ▁cycle