Why use a Google Sitemap?

Question

I've played around with Google Sitemaps on a couple sites. The lastmod, changefreq, and priority parameters are pretty cool in theory. But in practice I haven't seen these parameters affect much.

And most of my sites don't have a Google Sitemap and that has worked out fine. Google still crawls the site and finds all of my pages. The old meta robot and robots.txt mechanisms still work when you don't want a page (or directory) to be indexed. And I just leave every other page alone and as long as there's a link to it Google will find it.

So what reasons have you found to write a Google Sitemap? Is it worth it?

Answer 1

From the FAQ:

Sitemaps are particularly helpful if:

• Your site has dynamic content.
• Your site has pages that aren't easily discovered by Googlebot during the crawl process—for example, pages featuring rich AJAX or images.
• Your site is new and has few links to it. (Googlebot crawls the web by following links from one page to another, so if your site isn't well linked, it may be hard for us to discover it.)
• Your site has a large archive of content pages that are not well linked to each other, or are not linked at all.

It also allows you to provide more granular information to Google about the relative importance of pages in your site and how often the spider should come back. And, as mentioned above, if Google deems your site important enough to show sublinks under in the search results, you can control what appears via sitemap.

Answer 2

I believe the "special links" in search results are generated from the google sitemap. What do I mean by "special link"? Search for "apache", below the first result (Apache software foundation) there are two columns of links ("Apache Server", "Tomcat", "FAQ").