Highlights characters in HTML text with emphasis, usually italics.
None.
<EM> ... </EM> is legal within:
<A> <ADDRESS> <B> <CITE> <CODE> <DD> <DT> <EM> <H*> <I> <KBD> <LI> <P> <PRE> <SAMP> <STRONG> <TT> <VAR>
The following markup can be used within <EM> ... </EM>
<A> <BR> <CITE> <CODE> <EM> <I> <IMG> <KBD> <SAMP> <STRONG> <TT> <VAR>
Wherever mild emphasis in text is needed. However, as with all layout tages, sparing use will keep the tag meaningful.
The most useful item in a workshop is the <EM>duct tape</EM>.