For me personally, it's _actively working_ with code more so than merely reading it. If I read code without a concrete goal, I find that I gloss over important

For me personally, it's _actively working_ with code more so than merely reading it. If I read code without a concrete goal, I find that I gloss over important details and fail to really grok the purpose and design of the code, and therefore do not learn all that much. However, if I'm actively debugging some code, or if I need to understand the consequences of calling some function in a library, then I feel like I get a much firmer grasp on the code, and consequently I properly absorb the techniques used in it. So I guess I'd rephrase the advice as: Read and understand all the code you're working with. Build as many systems as you can to expose yourself to more coding techniques. Don't take any tool or library you call into for granted- be diligent and read / understand your dependencies carefully. When something unexpected goes wrong, initially suspect everything in your stack until debug data tells you otherwise.