Command Query Responsibility Segregation (CQRS) is a design pattern that separates the read and write operations of a data store into distinct models. This separation is useful in systems that require scalability and have complex business logic, as it allows for optimized query performance and simplifies the management of complex domain logic. CQRS is particularly relevant in the methods-and-patterns quadrant because it provides a strategic approach to handling data operations in software architecture. It is placed in the assess ring, indicating that while it shows promise and can address specific architectural challenges, it should be evaluated carefully for suitability within the context of a project's requirements. CQRS can be especially beneficial when combined with Event Sourcing to provide a complete history of changes to the system’s state.