Design :
              The third phase of  SDLC  is  design in which analyst convert  the   description of recommended   solution is converted into logical and them physical system  specification. The analyst must design all aspect of system from input. Output  screen  report database etc. and then analyst must provide the  physical specification on of the system they have design either as a model or as a detailed document to guide those who will build a new system


                                        Logical design is the part design process  that is independent of  any specific  hardware or software platform. The  logical design concentrate on level of specification. physical design is the part of design process  in which the logical design of the system is transferred into specific detail. During the physical design the analyst team must determine many of the physical detail necessary to build a final system