Hypertext markup language is a markup-programing-language used to create hypertext. Most webpages has a HTML base (a .html file that can load more files) which is loaded when the client acesses the webpage. Here is some basic ways that you can use HTML to create simple hypertext features:

This will dispolay on a webpage like this: This is bold text: Bold Text

Italic Bold

The reason why the <br> tag is used after the <b> tag is because <br> creates a new line. If a <br> wasn't used the link would be on the same line as the italic and bold text because new lines in the code doesn't create a new line in the hypertext.

A span can be used to change the font but does nothing on it's own Italic

Did you notice that there is no new line after the <span> tag? that's because the <br> tag creates a new line in the hypertext and a new line in the code is just a way to structure the code.