In cloud computing, Elasticity refers to the ability of cloud systems to rapidly change the amount of resources allocated to a system based on its current demand. This is a key benefit of cloud computing that ensures that applications always have the right amount of resources.

Elasticity works by monitoring the load on a system and automatically adjusting resources as needed. This can involve adding more resources (scaling out) when demand is high and removing resources (scaling in) when demand is low.

This process is typically managed by auto-scaling services provided by cloud providers. These services use predefined rules and real-time metrics to determine when to scale resources. This automatic adjustment of resources helps businesses optimize their costs and maintain high performance.

A streaming service uses elasticity to handle changes in demand. When a popular event is being streamed and demand increases, more resources are automatically allocated to handle the load. Once the event is over and demand decreases, the resources are automatically reduced.