There is no long term contract with Google Adsense. You can choose to leave the program at any time. You will need to provide written notice by mail or email to Google. <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p> </o:p>

They are useful not only to the web sites (Google and many others) that use them, but also to people who are searching for a particular site and those who run web sites. Spiders allow your site to be seen by the millions of people who use search engines every day.