PMI defines the project management body of knowledge (PMBOK) as a term that describes the knowledge within the profession of project management. The project management body of knowledge includes proven traditional practices that are widely applied as well as innovative practices that are emerging in the profession.
The body of knowledge (BOK) includes both published and unpublished materials. This body of knowledge is constantly evolving. This PMBOK Guide identifies a subset of the project management body of knowledge that is generally recognized as good practice.
This PMBOK Guide is different from a methodology. A methodology is a system of practices, techniques, procedures, and rules used by those who work in a discipline. This PMBOK Guide is a foundation upon which organizations can build methodologies, policies, procedures, rules, tools and techniques, and life cycle phases needed to practice project management. (A Guide to the Project Management Body of Knowledge (PMBOK® Guide)–Sixth Edition; Project Management Institute-2017; Page 38, Page 39)