From http://www.w3schools.com (Copyright Refsnes Data)

HTML Text Formatting

This text is bold

This text is big

This text is italic

This is computer output

This is_subscript and ^superscript

HTML Formatting Tags

HTML uses tags like <b> and <i> for formatting output, like bold or italic text.

These HTML tags are called formatting tags.

Refer to the bottom of this page for a complete reference.

Text formatting
This example demonstrates how you can format text in an HTML document.

Preformatted text
This example demonstrates how you can control the line breaks and spaces with the pre tag.

"Computer output" tags
This example demonstrates how different "computer output" tags will be displayed.

Address
This example demonstrates how to write an address in an HTML document.

Abbreviations and acronyms
This example demonstrates how to handle an abbreviation or an acronym.

Text direction
This example demonstrates how to change the text direction.

Quotations
This example demonstrates how to handle long and short quotations.

Deleted and inserted text
This example demonstrates how to mark a text that is deleted or inserted to a document.

Tag	Description
<b>	Defines bold text
<big>	Defines big text
<em>	Defines emphasized text
<i>	Defines italic text
<small>	Defines small text
<strong>	Defines strong text
<sub>	Defines subscripted text
<sup>	Defines superscripted text
<ins>	Defines inserted text
<del>	Defines deleted text
<s>	Deprecated. Use <del> instead
<strike>	Deprecated. Use <del> instead
<u>	Deprecated. Use styles instead

Tag	Description
<code>	Defines computer code text
<kbd>	Defines keyboard text
<samp>	Defines sample computer code
<tt>	Defines teletype text
<var>	Defines a variable
<pre>	Defines preformatted text
<listing>	Deprecated. Use <pre> instead
<plaintext>	Deprecated. Use <pre> instead
<xmp>	Deprecated. Use <pre> instead