Can you explain the difference between horizontal and vertical scaling, and in what scenarios each would be preferable?

During my final year in college, I worked on a group project to develop a web application for managing campus events. We initially built it on a single server, which is a form of vertical scaling. As our user base grew during testing, we faced performance issues. I suggested that we could implement horizontal scaling by using multiple servers to handle different parts of the application. We set up a load balancer to distribute the traffic, which significantly improved the app's responsiveness. This experience taught me the practical implications of scaling in web applications and how to adapt to growing user demands.

I volunteered to help organize a community event that attracted a large number of participants. Initially, we had a small team of volunteers managing the event logistics, which is akin to vertical scaling where we were relying on our limited resources. As participation grew, I proposed that we recruit more volunteers to manage different areas like registration, food services, and activities. This approach mirrors horizontal scaling, where we added more 'units' to manage the increasing workload efficiently. By expanding our team, we ensured that the event ran smoothly and attendees had a great experience.

In my first job as an IT support intern, I often dealt with requests for additional server capacity. I learned that vertical scaling was frequently used for existing applications that required more power without changing the architecture. However, for new applications, we often used horizontal scaling to ensure better load distribution and reliability. For instance, when deploying a new customer support system, I participated in discussions about using multiple servers to handle varying loads. This experience helped me understand the strategic considerations behind scaling decisions in a professional setting.