ISO 9001:2015 is primarily guided by 7 principles, below we’ll give you a quick explanation on each of these and why there is focus on them specifically:

Customer focus: An organization can achieve sustained success when it focuses on customer needs and exceeding their expectations.
Leadership: Organizations maintain cohesiveness and internal engagement when they focus on establishing unity of purpose and direction in leaders at all levels.
Engagement of people: Enhanced capability to achieve set quality objectives is possible when employees at all levels are sufficiently informed and engaged.
Process approach: Consistency of quality services is achieved most efficiently when all activities and interrelated processes within the system are managed.
Improvement: Organizations can best maintain and surpass current performance levels by fostering an ongoing policy of continual improvement.
Evidence-based decision making: Organizations can make objectively better-informed decisions in regards to internal processes by analyzing and evaluating existing data and evidence.
Relationship management: Performance optimization is better achieved when organizations effectively manage relationships with supplier and partner networks that are existing/potential stakeholders towards sustained success.