A site map is an index of the pages on your web site and serves two purposes. It provides visitors with an alternative way to navigate your pages and it makes it easier and faster for the search engines to evaluate and rank your valuable information.
A good site map will let your visitors see your entire layout at a single glance. While most people will find their way around with normal navigation methods, for the few who need access to site maps, they will be crucial. When complex menu systems prevent your users from easily finding what they need, their frustration may cause them to leave your site and go somewhere else. A sitemap may be your only opportunity to keep them from moving on to your competitor.
As an index, the site map’s role in visitor navigation is urgent at the time, but the more mundane day to day purpose is to aid the robots. Your site maps are a key search engine optimization (SEO) tool. If a large percentage of your site is given over to flash elements, graphics and data base driven content, the site map may be the only way for the search engines to navigate at all. Even sites with more spider friendly designs can benefit from providing a direct path to the most important spots. Giving the search engines a specific list of places to go may give you a significant advantage, especially if you have thousands of pages or multiple sub domains.
Asking SEO professionals how to create site maps will get you a myriad of answers. That is partly because structure can vary so much. Smaller sites may need only a simple list of URLs. More complex operations could have a whole directory of indexes serving multiple purposes. Google advises having a separate map for each type of data on your site. They also look for Meta information on the frequency of changes, the last updates, and a description of the subject matter.
There are many index building sources available. You can do it yourself with tools furnished by the major search engines or by using software from third party vendors. You can also hire SEO companies to do it for you. The best method for you depends on the size and complexity of your website and your own technical expertise.
In the beginning, a site index was a simple text file with a list of URLs or links. Currently, site maps intended for visitors may be as simple as an alphabetical list or as complex as an interactive graphic. Whatever the style, a user map can simply be a page added to your root directory.
The more common method of preparing an index for SEO purposes is an XML file. Sitemaps.org provides detailed information and examples of how to set up a site index this way. The search engine data can be placed in the root directory, or a robot.txt file at that location can direct the crawlers to a sub directory. Complex operations may even use a specialized site map domain.
With this method, there is no real need to build a site map through each search engine’s webmaster tools interface. However, if you do not have access to the root directory or don’t feel capable of handling the XML, you can still do it that way. Once the site map is complete, you can submit it to the search engines through their Control Panels or by simply providing a robot.txt file.
Site maps have evolved greatly from their original design and purpose. While they are not a required element of good web design, they are necessary for good SEO. When planning a new website, creating a site map first can help to assure a more logical and accessible navigation system on completion. On older sites that may have grown convoluted or contain outdated pages no longer in use, it is an invaluable tool.
http://www.useit.com/alertbox/sitemaps.htm
http://en.wikipedia.org/wiki/Sitemaps
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