“using a sitemap to tell Google about how your site is structured.”
A site map provides information about all the pages and structure of a website that you want to be accessible to crawlers or users. The format can be a document or as an HTML webpage. It can be used as a planning tool for Web design as it gives an overview of the overall website design and how it is organized in a hierarchical fashion. The most used formats are the XML structured sitemap which is not intended for normal web users. It does convey information to the search engines about the pages in your site, their relative importance to each other, and how often they are updated. Of course, it is your intention to get all the pages indexed so that you have the maximum exposure for your website. Sometimes you may wish to hide a certain part of your site from the search engines.
Normally you should use a robots.txt file to communicate that but also the sitemap file can help. HTML sitemaps are the other frequently used format. This is designed to help the user find where the content he/she is looking for is on the site. This format does not need to include each and every subpage. There is software available that can automatically generate an XML file out of your website which is suitable for sending to the search engines and SEO-optimizers can help you generate such a file, both for user’s navigation usage as for usage to send directly to the search engines. When you make changes to your website the sitemap should be adapted. Having an automated method of updating the sitemap can help maintain up to date information with the search engines which in turn will keep your ranking high. Poor information with the search engines will lead to indexed pages that do not exist or live pages that are not indexed. Both cases mean that the website is not getting optimal results.
On the following site
There are also so you can find more information about what the protocol consists of www.sitemaps.org/protocol.php and below is an example part of such an XML file.
There are also some other possibilities with sitemaps. It is possible for instance to tell the search engines about how frequently the pages are updated, which can help the search engines determine how often they should look at your site in order to refresh the content and rank the site once again. If you intend to update the site frequently this may be an advantage. It is also possible to tell Google about the relevant importance of the different pages. In this way, the search engines can manage how to determine which pages are the key pages for the site and which are additional material or detail.