CMMI (Capability Maturity Model Integration) was published in 2001 by the Software Engineering Institute to guide process improvement across projects. It has two representations - staged and continuous. The staged representation has five maturity levels from initial to optimizing. The continuous representation has five capability levels from incomplete to optimizing, with each level building upon the prior ones to further define and manage processes. CMMI was expanded beyond software development to also cover systems engineering, product manufacturing, and people management.