Meta tags are used by search engines to see if they want to list your site as a result. This isn't the sole instrument used by search spiders, but it is a major one. So read on...
The meta tag has a variety of uses. The meta tag is used primarily to instruct search engine "spiders" on what to do with your page when they spider over them. It also is the tag used to cause a page to "refresh", or automatically reload and open up a new URL.
Keywords
<meta name="keywords" content="insurance, title,
real estate"></meta>
The keyword element states that the page concerns insurance, title, and real
estate and if someone does a search for these 3 words, that your page should
come up
as a search result. Repeating keywords will likely have your page removed
from a search engine's listings. In addition to that, if you are trying to
get visitors without actually earning them, then they won't stick around
and will likely never return. It is recommended that you limit your keywords
to 250 characters.
Page Description
<meta name="description" content="Title insurance
in Houston, Texas."></meta>
Tells search engines the description of your page. This can be as long as you
wish, but it is doubtful that a search engine will list the entire description.
It's wise to use some keywords in the description, as search engines also
rely on this data to rank pages. It is recommended that you limit your description
to 250 characters.
Expiration Date
<meta name="expires" content="31 December 2004"></meta>
Tells search engines when your page should be deleted from it's directory.
You should keep the date in the same format as I list it above [day month
year].
Author
<meta name="author" content="Your name here"></meta>
Tells people who designed the page.
Revisit-after
<meta name="revisit-after" content="30 days"></meta>
Tells the search engine to visit your site again in 30 days. This is good if
your site's description, keywords, or material changes often.
Distribution
<meta name="distribution" content="Global"></meta>
Tells the search engine that your site is meant for everyone, and that it can
be distributed globally. You can also specify "local" and "IU".
IU means Internal Use, which means that it's basically not meant for the
public.
No-cache
This next one tells the spider to not use a cached version of your website, and instead to use the most up-to-date version by downloading the site directly. A cached copy is a virtual snapshot of your web page that is used so that it's already on the engine's server, therefore letting user's download the page faster. The disadvantage is when your page contains info that is updated often and possibly has time-sensitive data, like news or recent announcements. So, if you have that kind of time sensitive data, use the "no-cache" option.
<meta http-equiv="pragma" content="no-cache"></meta>
Refreshment
In order to make another page load automatically, which is helpful when redirecting your visitors to a new address, you need to use the mighty meta tag. This is how it goes:
<meta http-equiv="refresh" content="10; url=http://www.here.com/newpage.html">
The part that says "content=10; url=http://www.here.com/newpage.html" is
the part of the code that says that the page specified will load after 10 seconds.
Robot Tags
There are some other META tags, also. Check out these "robot" tags that tell search engines whether or not to index the page, and whether or not to index pages that are linked to. There are many combinations of the robot tag. *Not all search engines can handle the robot tags as of now, but I'm sure they all will soon. It can't hurt to use them.
<meta name="robots" content="index,follow"></meta>
<meta name="robots" content="noindex,follow"></meta>
<meta name="robots" content="index,nofollow"></meta>
<meta name="robots" content="noindex,nofollow"></meta>