Which approach does horizontal scaling utilize?

Horizontal scaling, also known as scaling out, involves adding additional servers to a network to handle increased load rather than enhancing the capacity of existing hardware. This approach distributes workload across multiple servers, which allows for better management of traffic and data handling. By employing horizontal scaling, organizations can improve fault tolerance and system resilience; if one server fails, others can continue to operate, minimizing downtime.

The effectiveness of this scaling method lies in its ability to handle growth more flexibly. Rather than relying on a single, larger server that might become a bottleneck, horizontal scaling leverages multiple smaller, cost-effective servers that can be added incrementally as demand increases. This can also lead to more efficient resource usage and potential cost savings.

In contrast, the other approaches mentioned involve optimizing or upgrading current systems rather than expanding capacity through the addition of new servers.