What is the Scaling Cube, and how does it apply to microservices architecture?

The Scaling Cube (from 'The Art of Scalability') describes three independent axes for scaling a system: the X-axis (running multiple identical instances behind a load balancer — horizontal duplication), the Y-axis (splitting the application by function/service — which is exactly what microservices architecture does), and the Z-axis (splitting data by a key, like sharding by customer ID or region). Microservices architecture is essentially applying Y-axis scaling at the system level, and each individual microservice can then be independently scaled further along the X and Z axes.