Sitemaps

https://www.google.com/webmasters/tools/docs/en/
sitemapgenerator.html
The Google sitemap generator is an application that examines your Web site
and creates a sitemap based on the structure of the site. “But why do I need a
sitemap?” you ask.
Simple. A sitemap is the easiest way to get Google to crawl all the nooks and
crannies of your site. The problem is that the sitemap generator is a little difficult
to use.
First, you have to download the sitemap generator from the Web site listed
at the top of this section, and then you have to create a configuration file for
the sitemap. After that, you need to upload specific files to your Web site, run
the sitemap generator program, add the sitemap to your Google Webmaster
account, and set the process up to be repeated.
Those steps are a tough process to get through. If you’re really relying on
Google when it comes to your search engine ranking, though, this sitemap
generator is worth the time and effort.
If you’re okay with using a different sitemap generator, however, you might find
the XML Sitemap Generator (www.xml-sitemaps.com) a little easier to use.
All you have to do with the XML Sitemap Generator is enter the URL, wait for
the program to process, and then download the resulting file to your computer.
After that’s done, log in to your Google Webmaster account, add the
sitemap URL, and you’re good to go.
The sitemap is a tool — not a requirement. If you have a large site, you may
find that your AdSense results for deep pages are much better if you have a
sitemap in place to lead search engines to the pages.