Four days ago I was reading about what an API is. By day four I had a working RAG application running locally on my machine — one that could answer questions using documents I fed it, without sending anything to an external server. I'm still not sure how that happened. But I want to write it down before the feeling fades. Where this fits in the journey I'm midway through the IBM Applied AI Developer Professional Certificate. Courses 5 and 6 are where everything shifted — from understanding concepts to actually building things. Ten projects across five days. This isn't a course review. It's an account of what building actually felt like. Course 5 — Flask and backend development I went in thinking the backend would be manageable. I'd learned Node.js in my first year of college during a MERN stack module. I remembered the basics — routing, requests, how a server works. Enough to feel like I had a foundation. What I didn't account for: after first year, I completely stopped touching backend.…