My First System Design Class Taught Me More Than a Year of Coding

I walked into my first system design class expecting to write code. I walked out drawing boxes on a whiteboard and asking questions I had never thought to ask before. No syntax. No frameworks. Just shapes, arrows, and a deceptively simple prompt: Design a service where users paste in a long URL and get back a short one. That was it. The whole brief. Something every developer has used a hundred times — bit.ly, TinyURL, the link shortener baked into Twitter. I had never once thought about what...