Build real-world software by coding a Redis server from scratch. Network programming. The next level of programming is programming for multiple machines. Think HTTP servers, RPCs, databases, distributed systems. Data structures. Redis is the best example of applying data structures to real-world problems. Why stop at theoretical, textbook-level knowledge when you can learn from production software? Low-level C. C was, is, and will be widely used for systems programming and infrastructure software. It’s a gateway to many low-level projects. From scratch. A quote from Richard Feynman: “What I cannot create, I do not understand”. You should test your learning with real-world projects!