So there's a common kind of article that comes up a lot, and annoys me. It's the "What every programmer should know" or "needs to know" about this or that. About time, or names, or memory, or solid state drives or floating point arithmetic, or file systems, or databases.
Here's a good sampling on Hacker News of the kinds of things someone out there is insisting you absolutely have to know before you can knock out "Hello, World", or otherwise meet some higher standard for being a "real programmer".
I hate these articles.
For any one of them, you can find about 99% who don't already know something from the article, and yet they manage to somehow be productive enough that someone is paying to produce a product of value. To me, they come off as, "I want to be important, so I want to make it seem like my esoteric knowledge is much more important than it really is." If taken seriously, these articles would heavily skew your priorities.
So here's my standard for when you're justified in saying "what every programmer needs to know about X":
Think about the tenacious, eager kid from your neighborhood. He picks up on things really quickly. Once he learned to program, he was showing off all kinds of impressive projects. But he also makes a lot of rookie mistakes that don't necessarily affect the output but would be a nightmare if he tried to scale up the app or extend its functionality. Things you, in your experience, with your hard-earned theoretical knowledge, would never do. When you explain it to him, he understands what you mean quickly enough, and (just barely) patches that up in future versions.
What are those shortcomings? What are those insights, that this kid is lacking? What of this kid's mistakes would you want to give advice about to head off as soon as possible? That's what every programmer needs to know.
The rest? Well, it can wait until your problem needs it.