One of the most common system design interview questions is: "How would you scale a web application from 100 users to 100 million users? " The answer is rarely a single technology. Instead, systems evolve through multiple stages, with each stage solving a specific bottleneck.
Source: [Dev.to](https://dev.to/jaspreet_singh_86ae1740ac/how-systems-scale-from-0-to-100-million-users-3nm)