The period of time that begins when a software product is conceived and ends when the software is no longer available for use. The software lifecycle typically includes a concept phase, requirements phase, design phase, implementation phase, test phase, installation and checkout phase, operation and maintenance phase, and sometimes, retirement phase. Note that these phases may overlap or be performed iteratively.
System of Systems
Multiple heterogeneous, distributed systems that are embedded in networks at multiple levels and in multiple domains and are interconnected, addressing large-scale interdisciplinary common problems and purposes.
A system whose failure or malfunction may result in death or serious injury to people, or loss or severe damage to equipment, or environmental harm.