You only rally need one if you have a site that is difficult to reach some pages. A sitemap will help search engines find those pages. Otherwise they are not necessary.

The universally accepted sitemap format can be found at sitemaps.org.

According to my experience, Sitemap submission is very helpful to improve search rank. There are lot of free online sitemap tools are available. http://www.xml-sitemaps.com/ is one of best free site map generating tool.

They don't help rank at all. All they do is tell the search engines where to find your pages. That's it.

Sitemap is very much useful especially for users(visitors) and SEs crawling your site. Using sitemaps has many benefits, not only easier navigation and better visibility by search engines. Sitemaps offer the opportunity to inform search engines immediately about any changes on your site. Of course, you cannot expect that search engines will rush right away to index your changed pages but certainly the changes will be indexed faster, compared to when you don't have a sitemap.

You can use this link to generate one and submit it to Google and Yahoo...

Yes, sitemap is a really great help to a site. It helps not only the user but also to web crawlers or spiders to easily index your links.

Both HTML and XML sitemap helps... Like HTML will help your visitors if they want a simple view of linking of your website in one page..

and XML will give an easy direction to search engine crawlers for your web pages to index more quickly.

How many links do you typically put on your sitemap. I have read articles with varying opinions.

Would you put every link on it or only the more important pages?

For an HTML sitemap you need to keep users with dial up in mind and limit the size of a page. In those cases multiple sitemaps may be needed.

With an XML sitemap you should put every page.

I see, good point. so, even if your site have 1000s of pages , your saying to still put all those links on the XML version, but seperate the HTML version into multiple pages.

Ok, I am going to make sure my XML sitemap is setup right.

Thanks!