In what situations is it recommended to apply horizontal scaling of the system?

Horizontal scaling of the system is recommended when it is necessary to increase the performance and stability of the application by adding new servers or nodes, rather than increasing the resources of a single server (vertical scaling). This is especially relevant in the following situations:

• High load that a single server cannot handle.
• The need to ensure fault tolerance and load balancing.
• Systems with distributed architecture, such as microservices.
• When the application and infrastructure support horizontal scaling (e.g., sharded databases, caching).

Example: a web application serving a large number of users can be deployed on multiple servers with a load balancer to evenly distribute requests and ensure high availability.