This is the google webmaster guidelines, so for those that keep posting how can i hurt a competitor , its time to stop dreaming Our goal is to return highly relevant results for every query. Search results are returned from our search index. Our search index is constantly evolving as content is added and modified on the web. The changing content, as well as updates to our ranking algorithms, can cause URLs to change position in search results, and possibly, though less likely, be removed. There's almost nothing a competitor can do to harm your ranking or have your site removed from our index. If you're concerned about another site linking to yours, we suggest contacting the webmaster of the site in question. Google aggregates and organizes information published on the web; we don't control the content of these pages. Occasionally, fluctuation in search results is the result of differences in our data centers. When you perform a Google search, your query is sent to a Google data center in order to retrieve search results. There are numerous data centers, and many factors (such as geographic location and search traffic) determine where a query is sent. Because not all of our data centers are updated simultaneously, it's possible to see slightly different search results depending on which data center handles your query. We understand that these changes can be confusing. If your site is well-linked from others on the web, it's likely that we'll add it again during our next crawl. While we can't guarantee that any page will consistently appear in our index or appear with a particular rank, our Webmaster Guidelines offer helpful tips for maintaining a crawler-friendly site. Following these recommendations should increase the likelihood that your site will show up consistently in our search results.