What is the difference between scalability and elasticity in IT systems?

The distinction between scalability and elasticity in IT systems is vital for understanding how systems can adapt to varying loads and demands. Scalability refers to the capability of a system to handle increasing workloads by upgrading resources, which can involve adding more hardware or increasing the power of existing resources. This process can be linear, meaning that as demand grows, additional resources can be added in a predictable manner.

On the other hand, elasticity pertains to the system's ability to automatically adjust its resources based on current demand. This means that when there is a spike in usage, the system can expand to accommodate that demand, and when the demand decreases, it can retract its resources accordingly. This elasticity allows for dynamic resource management, making it particularly advantageous in cloud computing environments, where costs can be minimized by only utilizing resources as needed.

Understanding this nuanced difference enhances an IT professional's ability to design and implement systems that are not only robust and scalable but also adapt to varying levels of user demand efficiently. The other options do not accurately capture these definitions as they either mischaracterize the concepts or confuse their distinct characteristics.