What is CMM (SEI Capability Maturity Model)?
   According to the Carnegie Mellon University Software Engineering Institute, CMM is a common-sense application of software or business process management and quality improvement concepts to software development and maintenance. It's a community-developed guide for evolving towards a culture of engineering excellence, model fororganizational improvement .

   The Capability Maturity Model for Software (CMM) is a framework that describes the key elements of an effective software process. There are CMMs for non software processes as well, such as Business Process Management (BPM). The CMM describes an evolutionary improvement path from an ad hoc, immature process to a mature, disciplined process. The CMM covers practices for planning, engineering, and managing software development and maintenance. When followed, these key practices improve the ability of organizations to meet goals for cost, schedule, functionality, and product quality. The CMM establishes a yardstick against which it is possible to judge, in a repeatable way, the maturity of an organization's software process and compare it to the state of the practice of the industry. The CMM can also be used by an organization to plan improvements to its software process. It also reflects the needs of individuals performing software process, improvement, software process assessments, or software capability evaluations; is documented; and is publicly available.

   Capability Maturity Model Integration (CMMI) Maturity Levels The Five Maturity Levels described by the Capability Maturity Model. They can be characterized as per their primary process changes made at each level as follows:
Level 1: Initial The software process is characterized as ad hoc, and occasionally even chaotic. Few processes are defined, and success depends on individual effort and heroics.
Level 2: Repeatable Basic project management processes are established to track cost, schedule, and functionality. The necessary process discipline is in place to repeat earlier successes on projects with similar applications.
Level 3: Defined The software process for both management and engineering activities is documented, standardized, and integrated into a standard software process for the organization. All projects use an approved, tailored version of the organization's standard software process for developing and maintaining software.
Level 4: Managed Detailed measures of the software process and product quality are collected. Both the software process and products are quantitatively understood and controlled.
Level 5: Optimizing Continuous process improvement is enabled by quantitative feedback from the process and from piloting innovative ideas and technologies.
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