Horizontal and vertical scaling are two approaches to increasing the capacity of a system to handle increased load or traffic.

Vertical Scaling (Scale Up) involves adding more resources to a single server or node, such as increasing CPU, RAM, or storage. This method is often simpler to implement, as it requires upgrading existing hardware rather than adding new machines. However, vertical scaling has limitations due to the maximum capacity of a single server, which can lead to single points of failure and can be more expensive as it often involves specialized hardware upgrades ²³.

Horizontal Scaling (Scale Out), on the other hand, involves adding more servers or nodes to distribute the load across multiple machines. This approach allows for greater scalability, as there is no theoretical limit to the number of servers that can be added. Horizontal scaling is particularly beneficial for distributed systems and can handle unpredictable loads more effectively. However, it can be more complex to implement due to the need for load balancing and coordination between nodes ¹²³.

In summary, the choice between horizontal and vertical scaling depends on the specific requirements of the application, including expected load, budget, and system architecture.