Latent Semantic Indexing: What It Is!

By Gary Marsh, copyright 2007

Latent semantic indexing is a system that attempts to improve the service offered by most search engines to those using their services.

Keyword optimization has been the main part of search engine optimization from day one. The two major factors influencing search engine placement is keywords and backlinks.

When Google Adsense came along, it soon became apparent to crafty marketer's that there was a lot of money to be made by generating web-pages specifically designed to display Adsense ads. Thousands of dollars were being made daily by marketer's generating thousands of pages, using template-based page generation software. Content duplication was and still is all over the web because of this. The websites using these software generators were of little or no use to the visitor. Why? They were presented with nothing more than Adsense advertisements.

The biggest reason for the introduction of latent semantic indexing was to overcome this problem, and to ensure that websites were providing a useful service to those using Google’s search engine.

Ever since LSI came along, many sites have been de-listed by Google as being of little use to the visitor, and for using duplicate content. A change of the primary keyword was most generally the only difference between pages and even sites. Many black hat internet marketers found their income slashed to almost zero overnight. This change can often be traced back to the time that latent semantic indexing was put to use.

Latent semantic indexing was initially used in Adsense to enable adverts targeted to the theme of a webpage to appear on the page. The algorithm checks the wording on the page and determines the theme of the page. It was only later that Google applied the algorithms to search engine placement, and it is used by search engines other than Google. It involves analysis of words used in natural language, the synonyms and closely related words used when discussing the general theme of a page. It complements, rather than replaces, keyword analysis. No longer do you need to worry about keyword density...

Since it is based on a mathematical set of rules, or algorithm, it is not perfect and can lead to results which are justifiable mathematically, but have no meaning in natural language. Google purchased a company, Applied Semantics, to develop it early in 2003.

So what is latent semantic indexing? Let's explain this is simpler terms...

LATENT:

Present, but not evident or active

SEMANTIC:

Of, or relating to meaning.

INDEXING:

This is the guide that brings you your servings... This is your catalogue of choosing!

Let's get back to adsense... Generated pages used for Adsense are usually very general and are able to be used as templates for any keyword or keyword phrase.

This is very common with Adsense sites. You can replace the key-phrase with any keyword you want and the same text can be used over and over. This is why latent semantic indexing was introduced to search engine ranking analysis.

The ‘latency’ referred to in the term ’latent semantic indexing’ is the hidden meaning of the word, which remains hidden in the first version until the semantics of the second reveal its meaning. Thus, by use of the LSI algorithm, website content with similar keywords, but different meanings for the keywords, can be differentiated and, more importantly for the webmaster, the relevance of the site can be properly determined and indexed.

No longer will sites with ambiguous keywords be acceptable to search engines. The semantics of the page must make the meaning and topic of the page clear.

So what does that mean to you? Write for your target audience and use proper keywords to explain the concept. Don't worry so much about keyword density and appeasing to the search engines. If you appease your reader, you will in turn appease the search engines. Thus, your sites pages will rank higher and you'll be considered more of an authoritative website.

Gary Marsh is an SEO Agent & Expert. He has been working on the Internet since 1995, and is the Owner of BizNiche Marketing Solutions, a company providing low cost search engine optimization, submission and web promotion services.