This paper explains one of the most useful regulations in relation with managers and customers known as “CRM” . ”CRM“ is an acronym which is comprised of three main words , “CUSTOMER” , “RELATOINSHIP” & “MANAGEMENT” .”CRM“ includes all aspects of the exchange with customers and make whole elements within an organization relevant which are in relationship with customers one of the most important rules in “CRM” is 4P formula .4P is an abbreviation which is combined of PRICE” , “PRODUCT” ,”PROMOTION” & “PLACE” .Customer life time value ,“CLV” , is one of the possible tools to measure this relationship .