This is really a reminder as you learned about these in The W3C and Web standards.
By using the correct DOCTYPE declaration and a decent HTML/CSS editor you should find yourself sticking to standards. These tutorials are all based on W3C standards. You have probably seen by now that just because something works in one or two browsers doesn't mean it will work in all of them.
Get into standards habits by using the strict XHTML DTD and using the W3C validation pages before you publish any page.
By keeping to standards you can be sure that if any problems arise with your pages at least it wasn't your fault.
