Physical style tags indicate exactly how text is to formatted. For example Bold, Underline.
The following HTML tags are examples:
<b>
<i>
<u>
<tt>
<s>
<big>
<small>
<sub>
<sup>
Examples of these tag in use:
<b> This is bold text. </b>
which looks like this in HTML
This is bold text.
<i> This is italic text. </i>
which looks like this in HTML
This is italic text.
<u> This is text is underlined. </u>
which looks like this in HTML
This is text is underlined.
<tt> This is fixed width text. </tt>
which looks like this in HTML
This is fixed width text.
<s> This is text is struck through. </s>
which looks like this in HTML
This is text is struck through.
This is normal text. <big> This is bigger text. </big>
which looks like this in HTML
This is normal text.
This is bigger text.
This is normal text. <small> This is smaller text. </small>
which looks like this in HTML
This is normal text.
This is smaller text.
X<sub>1</sub> is subcripted (1).
which looks like this in HTML
X1 is subscripted (1).
X<sup>2</sup>. the squared (2) is superscripted.
which looks like this in HTML
X2. the squared (2) is superscripted.
Fractions can be made up with Sub/Superscripts. For example:
<sup>1</sup><sub>2</sub>
gives
12