Source : Free On-Line Dictionary of Computing

software life-cycle
     
         The phases a software product goes through
        between when it is conceived and when it is no longer
        available for use.  The software life-cycle typically includes
        the following: {requirements analysis}, {design},
        construction, testing ({validation}), installation, operation,
        maintenance, and retirement.
     
        The development process tends to run iteratively through these
        phases rather than linearly; several models (spiral, waterfall
        etc.) have been proposed to describe this process.
     
        Other processes associated with a software product are:
        quality assurance, marketing, sales and support.
     
        (1996-12-27)