HTML provides two types of text-level formatting: physical and logical styles. Logical styles are different in that they do not specify the physical properties of the text. Rather they specify the purpose for the text. The idea here is that the browser can then render the font (knowing what its purpose is) based upon the user's cultural environment or other variables. For example, in the US to show emphasis we generally italize things first. However, in another country, it may be standard to underline or bold instead. Thus by telling the browser the text should rendered as "emphasis" the browser can decide (or be programmed) to show the various text components as preferred by the end-user.
The following examples display the logical styles available. Many of the styles presented in your book are not shown here because they require stylesheets to define the actual formatting of the text.
sample coding.