In this section of Professor's Coding Corner, there are some tutorials I have written to explain some things that I had difficulty learning myself. In my years as a teacher, I found that you never REALLY learn something until you can explain it to somebody else. This holds true for website coding, as well.
Since there are many different browsers that people use to view the internet, a good web programmer needs to make sure that his site acts properly in them all. I always check my work in the top three browsers ( Chrome, Firefox, and Internet Explorer ), as these are used by the vast majority of viewers. Since my time is limited, I don't bother with the less popular browsers.