Meta tags, do they all have a use?

I'm interesting to know, are all these various meta tags actually required for search engines? Do they make a significant difference to the position of your site or should we just leave them out?

The tags below were generated by an online meta tag tool. I wasn't aware some of them even existed, I have only been using, the title/keywords and content tags which I consider the 3 most important. Am I wrong in thinking that?

<META HTTP-EQUIV="Content-Language" CONTENT="EN">
<META NAME="distribution" CONTENT="Global">
<META HTTP-EQUIV="Expires" CONTENT="Tue, 07 Jun 2005 18:45:32 GMT">
<META NAME="revisit-after" CONTENT="">
<META NAME="robots" CONTENT="FOLLOW,INDEX">

There are probably tens of meta tags, eash SE has its own rules about meta tags, most of those are ignored...
Here is an example of some of the other meta tags that arent well know

<meta name="document-type" content="Public">
<meta name="document-rating" content="General">
<meta name="DC.LANGUAGE" content="English">
<meta name="doc-publisher" content="company name">
<meta name="Publisher" content="company name">
<meta name="topic" content="Internet Services,Web Hosting">
<meta name="document-classification" content="Business and Economy">
<meta name="classification" content="Business">
<meta name="content" content="Internet Services">
<meta name="DC.CREATOR" content="company name">
<meta name="DC.PUBLISHER" content="company name">
<meta name="DC.CONTRIBUTORS" content="company name">
<meta name="DC.Coverage" content="global">
<meta name="contactOrganization" content="company name">
<meta http-equiv="organization" content="company name">

Google doesn't take meta tags too seriously for obvious reasons: spam.

Semantics matter a LOT. Use header tags wisely (i.e. <h1>...<h6>)

When people link to you, make sure they use the EXACT same URL
The following URL's will all have different page ranks:
http://www.example.org/
http://example.org/
http://www.example.org/index.php
http://example.org/index.php


Also, make the title attribute of all the URLs that link to you as descriptive as possible because google will consider that when indexing your site.
Example:

There are many other things...but they can be found on google itself by searching for something like:

I ran into the problem of people linking to a site using both
www.example.com
and
example.com

Since SE's see this as two different pages, we 'forwarded' example.com to www.example.com using a 301 redirect in a .htaccess file. Which means... we told the SE bot that example.com was permenantly moving to www.example.com.

This had the effect of combining our SE rankings. Now, only www.example.com links show in the SERP's.

Take a look at slashdot.org. if you type www.slashdot.org, it turns into slashdot.org (in the address bar).. It's a nice trick I do on every website i work with now.

Brett

That is a really good idea Brett. Thank you for posting that. I never have thought of that before, and I run into the same problem. Some people like to add the www. while others (me) hate it.

Robson, I think I have mentioned this before, some search engines require them and others don't. I put them into my websites regardless, since I want my site to be as accessible to as many search engines as possible. Do you want to possibly restrict your sites?

Here's the meta tags I use:

Originally Posted by madpenguin2 I ran into the problem of people linking to a site using both www.example.com and example.com Since SE's see this as two different pages, we 'forwarded' example.com to www.example.com using a 301 redirect in a .htaccess file. Which means... we told the SE bot that example.com was permenantly moving to www.example.com.

Oh that's a very good point...using the right HTTP status codes are very important.
Also, you guys are aware of robots.txt right? Some SE's don't behave according to robots.txt though :/

"<META HTTP-EQUIV="Expires" CONTENT="Tue, 07 Jun 2005 18:45:32 GMT">" - what does this actully do? infact half of these i have no clue.

I think it may be something to do with the way IE handles the cache.

Meta tags are still used by smaller search engines, and it's still better to use them than not at all.