Recently, I was overlooked for an opportunity because they wanted someone with production experience of building something out at scale for a user base of 100k or more. While that's good feedback to start with, I had trouble visualizing 'scale'. I mean, I currently work for a company with a user base of approx. 300k but I didn't build its frontend/backend that got it this far.
What does building for scale even mean? What does it look like on the front-end vs back-end?
When I think of scale, I'm thinking DevOps and ensuring your servers can handle 'scale' and setting up distributed databases, using caching (Redis).
So if tomorrow you were to start up a project, full stack work, how would you ensure it's scalable so that it can handle a mass influx of users the next day (extreme example much)?