Text Basics - HTML and XHTML: The Definitive Guide - page 133

all you want is italic. Alternatively, you can include text display-altering
cascading style definitions in your document. [ The <i> Tag, 4.5.4 ]
Besides for emphasis, also consider using <em> when presenting new
terms or as a fixed style when referring to a specific type of term or
concept. For instance, one of O'Reilly's book styles is to specially format
file and device names. You might use the <em> tag to differentiate those
terms from simple italics used for emphasis.
4.4.7. The <kbd> Tag
Speaking of special styles for technical concepts, there is the <kbd> tag.
As you probably already suspect, it is used to indicate text that is typed
on a keyboard. Its enclosed text typically is rendered by the browser in
a monospaced font.
The <kbd> tag is most often used in computer-related documentation and
manuals, such as in this example:
Type <kbd>quit</kbd> to exit the utility, or type
<kbd>menu</kbd> to return to the main menu.
4.4.8. The <samp> Tag
The <samp> tag indicates a sequence of literal characters that should
have no other interpretation by the user. This tag is most often used
when a sequence of characters is taken out of its normal context. For
example, the following source:
The <samp>ae</samp> character sequence may be converted
to the &aelig; ligature if desired.
is rendered by Netscape, for instance, as shown in Figure 4-9 .