What is Capability Maturity Model Integration?

Legal Definition
Capability Maturity Model Integration (CMMI) is a process level improvement training and appraisal program. Administered by the CMMI Institute, a subsidiary of ISACA, it was developed at Carnegie Mellon University (CMU). It is required by many DoD and U.S. Government contracts, especially in software development. CMU claims CMMI can be used to guide process improvement across a project, division, or an entire organization. CMMI defines the following maturity levels for processes: Initial, Managed and Defined. Currently supported is CMMI Version 1.3. CMMI is registered in the U.S. Patent and Trademark Office by CMU.
-- Wikipedia
Legal Definition
A framework that describes the key elements of an effective product development and maintenance process. The Capability Maturity Model Integration covers best-practices for planning, engineering and managing product development and maintenance. CMMI is the designated successor of the CMM.