CQRS, or Command Query Responsibility Segregation, is a software architectural pattern that separates the handling of data modification (commands) from data retrieval (queries). This approach allows developers to optimize each side independently, improving performance and scalability. By separating these responsibilities, systems can be designed to handle complex business logic more effectively. In a CQRS system, commands are responsible for changing the state of the application, while queries are focused on reading data. This separation can lead to more straightforward code and better organization, making it easier to maintain and evolve the system over time.