There are a number of reasons why your site may not be listed. The Google website explains why this may be the case. I have included the full explanation here.
A. My web pages have never been included in the Google index.
Google is a mechanized search engine, which employs robots known as ‘spiders’ to crawl the web on a monthly basis and find sites for inclusion in the Google index. Please review the basics of submitting your site to learn more.
1. Reasons your site may not be included.
* Your pages are dynamically generated. We are able to index dynamically generated pages. However, because our web crawler can easily overwhelm and crash sites serving dynamic content, we limit the amount of dynamic pages we index.
* You employ doorway pages. Google does not encourage the use of doorway pages. We want to point users to content pages, not to doorways or splash screens.
* Your page uses frames. Google supports frames to the extent that it can. Frames tend to cause problems with search engines, bookmarks, emailing links and so on, because frames don’t fit the conceptual model of the web (every page corresponds to a single URL). If a user’s query matches the site as a whole, Google returns the frame set. If a user’s query matches an individual page on the site, Google returns that page. That individual page is not displayed in a frame — because there may be no frame set corresponding to that page.
If you are concerned with the description of your site as seen by search engines, please read “Search Engines and Frames”. It describes the use of the ‘NoFrames’ tag, which is used to provide alternative content. If, instead of providing alternative content, you use wording such as “This site requires the use of frames” or “Upgrade your browser”, then you are excluding both search engines and people who use browsers with frames turned off. (For example, audio web browsers, such as those used in automobiles and by the visually impaired, typically do not deal with frames, which are a visual mechanism.) You can read about NoFrames in the HTML standard here: http://www.w3.org/TR/REC-html40/present/frames.html#h-16.4
2. Google does not index all of my pages. Why?
Although we index more than 8 billion web pages, we cannot guarantee that we will crawl all the pages on a particular site. However, we are always working to increase the number of pages we crawl and hope to include more pages in our index soon. For more information about how we find and include pages in our index please read our technology overview.
If your site’s internal link structure does not provide a path to all your pages, our robot may not see all the pages on your site. Google follows links from one page to the next, so pages that are not linked to by others may be missed.
Basically, you can’t buy your way into our actual search results. You can however, purchase advertising adjacent to Google results. More information about that program can be found here.
B. My web pages used to be listed and now they aren’t.
1. Changes from one index to the next.
Each time we update our database of web pages (about once a month), our index shifts: we find new sites, we lose some sites, and site rankings change. If your site was dropped from Google and you have not made major changes to it in the last month, we will likely pick it up again in our next index. It’s possible your site was simply inaccessible when our robots tried to crawl it.
You may want to check and see if the number of other sites linking to your URL has decreased. This is the single biggest factor in determining what sites are indexed by Google, as we find most pages when our robots crawl the web and jump from page to page via hyperlinks. To find out who links to your site, use Google’s link: tool.
It’s also possible your rank decreased because other sites were found and assigned a higher rank. You can be assured that no one at Google has hand adjusted the results to boost the ranking of a site. Google’s order of results is automatically determined by several factors, including our PageRank algorithm. Please check out our “Technology Overview” page for more information on how this works.
2. Multiple indices
We update our index about every four weeks. If you happen to enter the same query repeatedly while we are in the process of posting the index at our various data centers around the country, it might seem like you are seeing inconsistent results from Google. What is actually happening is that you are seeing a result from an ‘old’ version of our index one time and a result from a ‘new’ version the next. Due to the size of our index, we can not simultaneously post a new index at all of our data centers, which may result in this behavior for a short period of time.
3. Other reasons
If your page does not appear at all, here are some other possible explanations.
* Your site may not have been reachable when we tried to crawl it because of network or hosting problems. When this happens, we retry multiple times, but if the site cannot be crawled, it will not be listed in our current index. If it was a transient problem, your site will likely show up in the next index, which will be completed in a few weeks.
* A technical glitch on our side may have caused us to ‘miss’ your site. In crawling more than 8 billion pages, our system experiences hiccups from time to time. Again, this is a transient problem, and your site will likely show up in the next index. Please be patient with us during this period, as we are not able to modify our index by hand to add sites missed in this way.
* The contents of your page or the links pointing to your page changed significantly and you no longer have a sufficiently high PageRank, or your page had low PageRank to begin with and a small change caused you to be dropped from the Google index.
* Your page was manually removed from our index, because it did not conform with the quality standards necessary to assign accurate PageRank. We will not comment on the individual reasons a page was removed and we do not offer an exhaustive list of practices that can cause removal. However, certain actions such as cloaking, writing text that can be seen by search engines but not by users, or setting up pages/links with the sole purpose of fooling search engines may result in permanent removal from our index. If you think your site may fall into this category, you might try ‘cleaning up’ the page and contacting us with a re-inclusion request. We do not make any guarantees about if or when we will re-include your site.
