A maturity level is a well-defined evolutionary plateau toward achieving a mature software process. Each maturity level provides a layer in the foundation for continuous process improvement.
In CMMI models with a staged representation, there are five maturity levels designated by the numbers 1 through 5
1. Initial
2. Managed
3. Defined
4. Quantitatively Managed
5. Optimizing
CMMI Staged Represenation- Maturity Levels