One of the most common SEO recommendations these days is to use an XML site map file. But how important is a site map file for SEO?
An XML site map is a file you place on your website that lists some or all of the pages in your site. The idea is that search engine spiders can read the site map file(s), and locate all of your pages so they can be indexed. You can also give some useful information such as the relative priority of pages for crawling. XML site map files are used by all the major search engines, including Google, Yahoo and MSN/Live. For details on implementing sitemap files, see http://www.sitemaps.org/
So back to the question: How important are XML site map files?
The short answer is, like in so much of SEO: It depends.
The real answer goes back to the purpose of sitemap files: To help search engines find and crawl the pages on your website, and to do so efficiently. XML site map files do not have any direct impact on rankings. They only help search engines find pages.
For some search engines, such as Google, sitemap files are used for one other purpose: to help establish the “canonical” URL for content that is served under multiple URLS, and for deterining what URL to index when duplicate content is found. This can be very important if your site uses session IDs or other parameters in URLs, or serves the same content under different sections of the site.
Thus, the only time sitemap files will change your rankings is in how they help find pages sooner, or to find pages that can’t otherwise be found on your site by crawling links. It may also speed resolution of which URL to index in cases of duplicate content. It won’t actually increase rankings — it may just get them to rank sooner.
If your website does not change too often and is well structured, with HTML links that search engines can easily follow to find all of your pages, then using an XML site map file will probably make no real difference at all in rankings.
So when should you use XML site maps? Here are some examples:
- If your site is very large, you might use XML site map files to guide search engines to those pages that are new or change frequently so they are indexed sooner. This is useful even if your site is well structured for spidering.
- If your site has pages that are behind a search function, login, or other barrier to crawling by search engine spiders, then a sitemap file can get all of your content indexed. This is a primary purpose of site map files: to help find content that can’t be found by crawling. Keep in mind, however, that a major disadvantage here is that these pages will generally have little or no page rank, since there is no internal page rank “flow” to the pages.
- If your site has lots of issues with session IDs, dynamic URLs and duplicate content, then an XML site map file can help search engines to quickly determine the canonical URL for the content. This can speed indexing and ensure the canonical URL is shown in search results. Of course, if your site has these types of issues, you should work on them, but an XML site map file can help in the interrim.
- If your website has frequent new or changed content, you can use site map files to guide search engines to crawling those new pages first. Simply use the priority field in the sitemap records. Note that in this case you would only need to list new/changed pages. Removing a page from a sitemap file will have no impact once the page is found and initially indexed.
In general, it is a good idea to have an XML site map file. It helps search engines find all your good content, and you can use the priority field to help them discover and index new/changed content more quickly. However, don’t expect a big change in rankings just because you use a site map file. Think of it as a “best practice” that is part of your overall SEO strategy.