If you develop WordPress sites, chances are that you know a lot of functions, and how to use them. But there are quite a lot of them, and if you don't know them all, you might end up re-inventing the wheel for some of the sites you create. Because fortunately, WordPress already implemented most of the Wheel, and a lot of this Wheel is available as functions, that you can read about in the Codex. So it would make sense for you to learn them.
But going to the Codex and reading about every single function to see what they do is an effort that takes time. And in my opinion, it's better to just set this as one of your goals, and let something remind you later about this goal.
That's why, two weeks ago, I launched The Daily WordPress Reference newsletter to help people learn all the important WordPress functions. Every day. One at a time.
Right now, we're over 230 WordPress enthusiasts to receive one function reference every day.
Try it! It's free.
And if you like it, you should also follow the Daily WordPress Reference on Twitter. :)
Let me know what you think about it!