What Is Latent Semantic Indexing

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Latent Semantic Indexing (LSI) is a system used by Google and other major search engines (Update: read here, thanks for the Tweets, guys) The contents of a webpage are crawled by a search engine and the most common words and phrases are collated and identified as the keywords for the page. LSI looks for synonyms related to the title of your page. For example, if the title of your page was “Classic Cars”, the search engine would expect to find words relating to that subject in the content of the page as well, i.e. “collectors”, “automobile”, “Bentley”, “Austin” and “car auctions”.

Do Not Underestimate Content

SEO strategy has always denoted that great importance is placed on the page title and words encased in heading tags, especially the H1 tag. Words and phrases within the content that are bolded or italicized are also given a greater importance. But you should be aware of the use of LSI, as it can affect what keywords your website is ranked for.

But if your page contains synonyms, the search engine recognizes that your page is actually about the subject title and will place greater importance on the page. You may well already use good keyword techniques and add a few secondary keywords into your content, but the rest of the content should also be littered with synonyms to convince search engine spiders.

A Response to Keyword-Stuffing

Latent Semantic Indexing came as a direct reaction to people trying to cheat search engines by cramming Meta keyword tags full of hundreds of keywords, Meta description full of more keywords, and page content full of nothing more than random keywords and no subject-related material or worthwhile content.

Search engines, like Google, appreciate good content, and encouraging people to add good content that helps keep the high-ranked listings relevant. Although producing good content will not guarantee you first page rankings, it could improve your quality score.

When LSI is Not Relevant

LSI will not affect a squeeze page that has no intention of achieving a search engine rank anyway, due to its minimalistic content. But for site owners or bloggers hoping to get on the search engines good side, pay attention to LSI.

Latent Semantic Indexing is a good thing. It keeps content relevant and rich and benefits not only visitors, but website owners that produce quality material.

How to Befriend LSI

Latent Semantic Indexing is not rocket science, it is simple common sense. Here are some simple guidelines:

  1. If your page title is Learn to Play Tennis, make sure your article is about tennis.
  2. Do not overuse your keywords in the content. It could look like keyword stuffing and the search engines may red flag you.
  3. Never use Article Spinning Software – it spits out unreadable garble.
  4. If you outsource your content, choose a quality source.
  5. Check Google Webmaster Tools and see what keywords your pages are ranking for.

Latent Semantic Indexing is not a trick. You should bear it in mind when adding content to a web page, but do not get paranoid about it. The chances are if you provide quality, relevant content you will never have to worry about falling foul of and LSI checks.

Roko Nastic
Roko Nastic is writer and editor at WebmasterFormat.com, website developed to help webmasters build and maintain successful websites. Visitors to WebmasterFormat can enjoy a lot of useful tips, latest news and help in finding the best web hosts.
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  • http://twitter.com/safcblogger Dean Cruddace

    ♫ ♫ There may be trouble ahhhheaaad ♫ ♫

    • http://www.huomah.com theGypsy

      I have no idea what you mean? hee hee

  • http://www.greatwebsitesblog.com/ Barry Adams

    Dude, you’re in for a world of hurt… http://seobullshit.com/seo-myths-lsi-google/

  • http://twitter.com/i9webstudio tushar jadhav

    Nice info…thanks!

  • Hugo at Zeta

    I appreciate the effort, but I simply have not seen enough tangible evidence that Google (or any other search engine) is using LSI in any significant way. Search algorithms/AI are simply not that advanced yet.

    But maybe some day…

    In any case, that doesn't necessarily discount most the recommendations you've made in your post.

    • http://www.huomah.com theGypsy

      Actually quite the opposite Hugo, LSI is an older tech that isn't effected in large scale implementations for the most part. All modern engines use NLP/Semantic Analysis to some degree… just the flavours change.

      • http://www.thelostagency.com/ David Iwanow

        Agreed im sure ive got notes from some site written back in 2007, but doesn't it sound like you are worth more if you can offer an understanding on Latent Semantic Indexing to larger clients… and how cool does LSI sound ūüôā

      • http://www.searchengineoptimisation.com Phil

        I do not think LSI has much to do with new algo, however google says that new algo is 50% much faster and index new contents

  • http://twitter.com/aknecht Alan K'necht

    I'd love to see a well documented case study on this. Any takers out there?

  • http://www.huomah.com theGypsy

    OK…well, where to start?

    1. Google and LSI – the whole thing started when Google purchased Applied Semantics back in 2003 – strangely, for their ad matching technology NOT for an IR approach neccesarily. Google hoped it would, “”make online advertising more useful to users, publishers, and advertisers alike.””

    They spoke of their interest in, “Applied Semantics’ AdSense product that enables web publishers to understand the key themes on web pages to deliver highly relevant and targeted advertisements.”

    Did you catch that? Some odd program called ‘AdSense’ – hmmmm… sound familiar? This (purchase of Applied Semantics) is by no means evidence of Google’s use of LSI/A in the regular index,

    2. LSI isn’t considered to be an effective technology for large scale (organic) information retrieval. Edel Garcia (as now linked to in post) and others have made that case many times. Of more interest, along the lines of semantic analysis, are patent filings on phrase based (8 or so, last count) or the Google’s research blog’s interest in PLSA, HTMM back in 2007. Point being, the lease likely flavour is LSI. It simply needs to leave the SEO lexicon. Plain and simple.

    3. SEOs need, by and large, a greater understanding of ‘search engines’. I mean, the bloody term is 2/3rds of our title ‘search engine – optimization’. I can appareciate you trying to share concepts, it’s a noble cause, but we can only make ourselves look like tools by not having a firm grasp of that thing we optimize for. If not, we shall be forever known as nothing more than link whores and hype merchants.

    And there we have it… Roko, if you had been an ardent student and SEJ faithful reader, then it might have saved some grief reading a post I put on here a few weeks back about semantic analysis and SEO – https://www.searchenginejournal.com/understanding-semantic-search-and-seo/21134/

    Your ideas are sound, your knowledge of Google history and computer science, can probably use some polish. Feel free to email me any time you have questions or want to yak… can send a TON or papers, patents and insights for anyone seeking to learn more… Peace

    • Roko Nastic

      theGypsy, thank you for your comment and offer for learning materials. After reading links from comments and Ann's update, it seems that I could use some. I hope that readers will still find value in my post, after all, if search engines don't use LSI, they do use some other semantic indexing technology and tips in post are still applicable.

      • http://www.huomah.com theGypsy

        Sure thing, added ye on Twitter, feel free to DM fer my email and would be happy to assist in getting geekier in the future – Spreading the Gospel of the Geek bruddah!

  • dhirajch

    wow… nice post and great comment, Thanks both of you

  • http://www.makerealmoneyonline.biz Sue

    It's quite fascinating – all the different opinions on how Google works and how to keep them happy. Thanks for the insight!

  • http://www.searchengineoptimisation.com Phil

    I do not think LSI has much to do with new algo, however google says that new algo is 50% much faster and index new contents

  • samirthukral

    Thank you for all of comments….

  • http://twitter.com/kirkhamsEbooks KirkhamsEbooks

    Am I dense. The only thing I got out of this is don't cheat

  • http://www.infoline.in/ kaminiprajapati

    I understood that what is LSI but some one said Semantic SEO what it means?
    LSI & semantic SEO which is same or not?

  • http://www.hotworkpassport.com Mark Cody

    Quietly removing the Meta Keywords and this is so far more important – hopefully will stop the spammy sites from getting ahead I hope.

    Thanks for sharing.

  • http://www.stewartfireprotection.co.uk Jeff

    I only try to run my own business and find I am getting more scientific each month!!!! the labours of love !

  • http://www.webomnizz.com jogesh sharma

    first of all i really thankful to you for the explanation of LSI. i just want to know as you said in the last of your post that “do not use any article spinning software”,

    can i use some kind of software whose telling about the quality of the article?? Can i use this kind of software or not??

    i appreciate your kind help..

  • http://www.firesafetytraining.uk.com Mark Bleasdale

    Nice Post on LSI s and gives good explanation of how it works. Thanks for sharing.

  • http://theleafletdistribution.co.uk/ Nico Pirnazari

    my site effected with panda, if I do write and concentrate on Content writing, does LSI help to gain traffic back?

  • Ajaz

    Hey Roko,

    Great info but the “read here” link is broken.

  • http://technologyreads.blogspot.in/2013/08/seo-tips-for-2014-and-beyond.html Amit Dwivedi

    Thanks for your information, Literally I was little bit confused how to express the LSI, but after looking your blog i am sure, what exactly it is.

    Thanks again.

  • http://www.webdigitalservices.com Raven

    LSI in a simple term is rather then repeating the same words or phrases again and again we could use synonyms or related words of those keywords in the title basically.Hope I got it right. The post is in language even could be understood by a laymen

  • http://easysteps2buildwebsite.com Chaitanya

    It makes sense!! Using LSI keywords keywords instead of repeating the same target keyword again and again is definitely a good approach. However If the content is unique and complete then there we shouldn’t worry about LSI keywords.
    Thanks for the share..