Answer to Question 1
The five phases of the systems development life cycle are (1 ) system definition,
(2 ) requirements analysis, (3 ) component design, (4 ) implementation, and (5 ) system maintenance. Developers in the first SDLC phase, i.e. system definition, use management's statement of the system needs in order to begin to define the new system (for PRIDE, this statement is based on experience with the prototype). The resulting project plan is the input to the second phase, requirements analysis. Here developers identify the particular features and functions of the new system. The output of that phase is a set of approved user requirements, which become the primary input used to design system components. In phase 4, developers implement, test, and install the new system. Over time, users will find errors, mistakes, and problems. They will also develop new requirements. The description of fixes and new requirements is input into a system maintenance phase. The maintenance phase starts the process all over again, which is why the process is considered a cycle.
Answer to Question 2
Data is not free. There are costs for developing an information system, costs of operating and maintaining that system, and costs of time and salary for reading and processing the data the system produces. For data to be worth its cost, an appropriate relationship must exist between the cost of data and its value.
The phosphorus cycle.
Menstrual Cycle
Jan de Heem, Still Life with Lobster.
Life cycle of a club fungus having two mating strains of hyphae
Major cell cycle checkpoints
The lytic and lysogenic life cycles of a temperate bacteriophage