What are sources of best practice?

Customers, suppliers, and advisors are stakeholder categories in the service value chain, not defined sources of best practice knowledge in ITIL.

ITIL explicitly identifies several sources of best practice, including standards, industry practices, academic research, training and education, and internal experience. Industry practices represent proven real-world approaches adopted widely across organizations, academic research provides evidence-based theoretical grounding, and training and education formalize and transmit accumulated knowledge. Frameworks like ITIL itself are synthesized from these sources.

Substitutes, regulators, and customers describe elements of a competitive or compliance environment, not the knowledge sources from which best practices originate.

Competition, compliance, and commitments are business drivers or constraints that influence strategy, not recognized sources of best practice in the ITIL framework.