XML Sitemaps, (also known as Google Sitemaps) are accepted by all three major search engines as a source of information about your site. Google Webmaster Tools even has a spot where you can tell Google where to look for the sitemap, if you haven’t already told search engines about it by using your robots.txt file or just thrown it into the root directory. There are even websites that will spider your site for free and generate a sitemap for up to 50,000 URLs. (Just look in Google under XML Sitemap Generator.)

Even though it is usually pretty easy to create and install, do you really need an XML sitemap? If your site is small enough, the answer might be “No.” For instance, if you do a site: command on Google and see that all your pages are in the engine, then a sitemap isn’t going to find any more of them. While it is possible to set a “priority” for pages using the sitemap, you may be artificially downgrading the importance of ranking pages by selecting this feature. In the past, people abused this feature by selecting a priority of “1” for all pages, so search engines may very well be skeptical of user prioritization. Webmaster Tools will actually give you a warning if it thinks your priorities are skewed.

If you’ve got a website with thousands of URLs, or your inventory changes on a regular basis, then an XML Sitemap may be the way to go. In this case, you want to have it built into your shopping cart to automatically update when you make changes. We always caution customers that a sitemap isn’t going to improve rankings for pages that have already been cached, but it is an effective way of helping engines find new pages. Removing a deleted page from your sitemap also won’t get search engines to take them out of their indexes, so a 301 redirect is still the preferred way to deal with page changes.

If you’re launching a brand new site with a lot of pages, or making major architectural changes, then a Google Sitemap is a good idea. However, a redesign of an existing site should always include redirects for pages that are getting external links. If you have a site that is not getting interior pages crawled, XML Sitemaps might assist the search engine in finding those pages, by you should be cognizant of the fact that the site is somehow preventing a search engine from finding those pages all by itself. Generally speaking, if an engine can’t locate interior pages on its own, then you probably are missing a lot of PageRank and Link Popularity that should be flowing from the homepage to interior pages by way of well-constructed links and silos. Assuming that the search engine finds the new pages with the XML sitemap, it may not put much stock in them if they can’t be placed into their proper link context.

In most cases, people will just go ahead and install a sitemap as part of SEO best practices. It doesn’t take too much time, and as the old adage goes: “It can’t hurt.” For those special cases where installing the map takes more time, or involves the employment of a tech, there is a certain legitimacy to the question about the necessity of its installation. Since the XML sitemap is exclusively for search engines, it is only really necessary if they can’t find something or if wholesale changes are under way, but most people in the world of search engine optimization will just make sure it gets uploaded anyway. Therefore, XML Sitemaps usually get installed as part of the whole SEO package, but they shouldn’t take precedence over good internal linking, inbound link acquisition, a proper title structure, or content that makes your site a resource and not just a list of pages.