Latent semantic indexing can help overcome "vocabulary mismatch" problem when a human uses a search engine. Individual words do not always provide reliable evidence about conceptual meaning of a document. For instance, a Web page that is highly relevant to term "laptop" may never use term "notebook," however it is clear to a human being that "notebook" is often used as a synonym for "laptop."

While it is beyond scope of this article to discuss mathematics behind LSI, its implications for search algorithms are simple. LSI can use statistical techniques to create a semantic analysis for any given query topic. In practice, this means that a page can be considered relevant for a particular keyword, even if it does not contain that keyword. For instance, a page that is considered relevant for "laptop" can also be considered relevant for "notebook" even if it does not contain word "notebook," if LSI determines that "notebook" is semantically related to "laptop."

The principle can be applied to backlinks as well. Backlinks with anchor text that do not contain your Web site's main keyword, but instead contain a synonym or related word, may still be giving your site a bonus for main keyword.

Link Popularity Building Best Practice: Vary Your Anchor Text

The recent increase in penalties given to sites with unnatural backlink anchor text, along with possible implementation of LSI, should give webmasters motivation to vary their backlink anchor text heavily. Rather than seeking to only obtain links using their main keyword, webmasters should include synonyms, variations and related words. Certainly no single keyword variation should be used majority of time; rather, text of all links should vary widely, just as they would if links were obtained passively. This will ensure a site's improvement in SERPs, without drawing a penalty flag.

There is no way to know for sure if a new web site is in Sandbox, but best way to determine if you are in Sandbox is if your web site has a good amount of quality backlinks, quality content and a good ranking in other search engines, such as Yahoo!, MSN and Ask Jeeves, but still no where in Google's search engine results for your keywords.

It has been suggested by some that it can take up to 9 months before a new web site can get a high ranking in Google's search engine results and out of Sandbox, but this does vary from web site to web site. This Also depends on how competitive your new web site's market and keywords are.

There is no known way of speeding up amount time a new web site is in Sandbox. Before you fully put up your web site you could get a few backlinks to it before you fully put it up, even though you will still be in Sandbox this way, you won't waste much time. You could also buy a domain that's already being used, so you never have to be in Sandbox.