Nerdcore Rap on Web Design
Now this is a rapper I can relate to!
And now for a bit of nitpicking…
The Poetic Prophet here describes bold as "old and wrong" which I tend to disagree with. The tags <em> and <strong> are designed to be semantic phrase elements that happen to render the same as <b> and <i>.
In some cases, you might want to change the display of something but might not actually want to "emphasize" it (e.g. the title of a book). Ideally this would all be done through CSS, but sometimes it’s easier to just add a tag than create a new class selector.
My rule of thumb is, think about how people would read the text aloud, if you would actually emphasize it (or strongly say it), use <em> and <strong>, otherwise for now I think <b> and <i> are still cool.