What is the difference between horizontal scaling and vertical scaling?
Answer
A "horizontally scalable" system is one that can increase capacity by adding more computers to the system. This is in contrast to a "vertically scalable" system, which is constrained to running its processes on only one computer; in such systems the only way to increase performance is to add more resources into one computer in the form of faster (or more) CPUs, memory or storage.
Horizontally scalable systems are oftentimes able to outperform vertically scalable systems by enabling parallel execution of workloads and distributing those across many different computers.