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Systems development life cycle (SDLC) is a very important methodology that assists IT professionals in the development of methods and procedures for new or re-engineered systems.  
For this essay, imagine you are approached by a member of a business department that has no idea what SDLC is, and they want to know when a physical model is created. You must first describe the SDLC and its phases. Then, explain when a physical model can be created. Also, be sure to indicate which phase you think is the most important.  
Your essay should contain a minimum of 300 words. Format your essay using APA style. Use your own words, and include citations and references as needed to avoid plagiarism.