CQRS Command Query Responsibility Segregation - Separate the query side from the command side.

Use the CQRS pattern when

• you want to scale the queries and commands independently.
• you want to use different data models for queries and commands. Useful when dealing with complex domains.
• you want to use architectures like event sourcing or task based UI.

• Greg Young - CQRS, Task Based UIs, Event Sourcing agh!
• Martin Fowler - CQRS
• Oliver Wolf - CQRS for Great Good