tagging for dummies?

If you all can forgive a somewhat ignorant question, I'm trying
to understand "tagging". I've kept a blog for several years using
pyblosxom, and I like it a lot. But every now and then, some event
or organization will say something like "If you blog this, make sure
you set the FOO tag so we can find it".

I presume that's straightforward if you use one of the blogging
services, but how would I add tags to a pyblosxom entry? Is it
something that shows up in the RSS, in the HTML, or just part
of the entry text (like "tags: foo, bar")?  When search engines
look for blog tags, what are they looking for?

I tried googling but didn't find anything helpful. I found lots of
pages on generating tag clouds, alphabetizing tag clouds, searching
based on tag clouds, and replacing pyblosxom with other software
that generates tag clouds; but I couldn't find any basic pages
explaining what a tag is, what it looks like in the html and/or rss,
and how you'd add one to a pyblosxom entry.

Thanks for any help!

	...Akkana

-------------------------------------------------------------------------
This SF.net email is sponsored by: Microsoft
Defy all challenges. Microsoft(R) Visual Studio 2008.
http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/