We have just said that HTML tags are not case sensitive: <B> means the same as <b>, and when you surf the Web, you will notice that most tutorials use uppercase HTML tags in their examples.  This is no longer the proper standard to use.

We always use lowercase tags now. Why?
If you want to prepare yourself for the next generations of HTML, you should start using lowercase tags. The World Wide Web Consortium (W3C) recommends lowercase tags in their HTML 4 recommendation, and XHTML (the next generation HTML) demands lowercase tags.