This. Visibility into what is actually going on, and the drive to understand it. Troubleshooting, debugging, learning: all the same thing, but tarred with diffe

This. Visibility into what is actually going on, and the drive to understand it. Troubleshooting, debugging, learning: all the same thing, but tarred with different parts of the process. Dig into what's actually going on and understand the layer under you. tl;dr: Keep digging, because everything's worth knowing at some point. It's generally much easier to fix a bug in your own code or infrastructure if you're familiar with the innards of the things you depend upon directly, and learning your preferred platform beneath the current frameworks is a solid advantage because it helps you move sideways when the next New Framework comes along. But there's also the conceptual side, the general concepts which have remained unchanged for decades, which a detailed knowledge of a specific platform (eg. Java, .NET, Node.js) doesn't necessarily aid with. These probably won't even feel relevant on a daily basis, but will definitely multiply your effectiveness over the long term. Some things which might fall into that category: * SQL and relational databases (especially if you're not using SQL, because you'll be reinventing it for any nontrivial amount of data) * Consistency models and distributed systems (capabilities and limitations; some things can never be waved away by technology) * The operating system, and principles of its design (not necessarily in any great detail, but knowing roughly how software talks to hardware is very useful, especially when assessing the marketing blurb for any cloud platform) * Complexity theory (stringing three 'optimal' algorithms together might be textbook, but often you can apply some domain knowledge to cut out a step or two to reduce actual runtime and maintenance overhead) I've found stuff like graph theory, principles of compiler design, and a working knowledge of assembly code to be useful too, but that's probably the far end of the bell curve for web server stuff :P Computer Science is a subset of mathematics and it's amazing which bits of pure maths turn out to be useful in my day job. Shame I'm not very good at that stuff... but reading enough about it to recognise when it's applicable can mean the difference between 'picking a good library off the shelf' and 'hacking together a terrible solution myself'.