The load on different parts of the application is typically very different. For example, in the case of a flight booking application, a customer usually searches multiple times before making a decision on whether to book a flight. The load on the search module would typically be many times more than the load on the booking module. The microservices architecture provides the flexibility of setting up multiple instances of the search service with few instances of the booking service.

The following figure shows how we can scale up specific microservices based on the load:

Microservices 2 and 3 share a single box (the deployment environment). Microservice 1, which has more load, is deployed into multiple boxes.

Another example is the need for start-ups. When a start-up begins its operations, they are typically unaware of the extent to which they might grow. What happens if the demand for applications grows very fast? If they adapt the microservice architecture, it enables them to scale better when the need arises.