What is Latent Semantic Indexing?

Latent semantic indexing is a mathematical-based methodology that search engines use to determine the relationship between a web page’s keywords and other related concepts. More specifically, the algorithm synthesizes your website’s content, and looks for words related to the title as it crawls your page or post. For example, if your post is called “Best National Parks,” the search engine might expect to find words like “Yellowstone,” “Yosemite,” and maybe even “hiking trails” embedded within your text. Imagine the computing power it takes Google to return articles about SEO when viewers search on the word, “Panda.” How does Google know whether to return articles about the animal or the algorithm update? Because of latent semantic indexing.

Breaking Down the Terms

✔ Latent = existing but not yet developed or manifest; underlying
✔ Semantic = relating to meaning in language or logic
✔ Indexing = A search engine’s way of collecting, parsing, and storing data to quickly and accurately retrieve information

Why Is Latent Semantic Indexing Important?

related keywords help clarify meaning for search enginesThe English language has many ambiguous words and phrases. The classic example we may remember from our childhood comes from the book, Eats, Shoots and Leaves – a lovely story that illustrates punctuation’s role in clarifying semantics (meaning).

Let’s look at some other ambiguous phrases that can’t be clarified by punctuation and need context for clarity:

  • We watched her duck
  • Teenagers are hunting dogs
  • I saw a person across the street with a telescope

With the help of contextually related keywords, search engines are able to determine the meaning of the main keyword and return relevant search results. Having naturally occurring related words in your post, therefore, helps  your website rank higher in the search engine’s query return. That is why all SEO experts need at least a basic understanding of LSI.

Why Did LSI Come About?

Google always has been dedicated to developing algorithms that deliver the most relevant search results so more and more people will choose Google as their primary search engine. The more people who use Google, the more advertising it can sell. The more money it earns, the more it can invest in technology dedicated to perfecting search results which in turn keeps competitors at bay. And so on.

Search algorithms were quite simple at first, but as the internet grew, returning relevant search results became more complex. Seeing this, marketers began stuffing as many keywords into their <H> and <p> tags as possible, making it easy for Google to find and return their pages. SEO experts aimed for keyword densities of 10%+, cramming their keywords in wherever they could. The result was clunky, awkward sites that were undeniably spammy. Then, search engines began to prioritize LSI keywords in response to keyword stuffing. Nowadays, however, search engines have become sophisticated enough to use LSI keywords to determine context. For instance, if a primary keyword for a certain page is “tidal wave,” some LSI keywords might be “ocean,” “tsunami,” and “warning.” The search engine will assume you are talking about a physical ocean tidal wave. However, if the LSI keywords were “music,” “Jay Z,” and “streaming services,” the search engine would assume you’re talking about Jay Z’s new streaming service, Tidal Wave.

When Did Search Engines Start Using LSI?

In 2013, Google introduced a new update to its search algorithm called Hummingbird. With Hummingbird, LSI was broadly applied. The update gave Google the ability to holistically synthesize search queries. That is, prior to Hummingbird, Google had not yet mastered the method of understanding how other terms relating to your keywords fit together. Before, the search engine would try to find pages that matched your individual words. Post Hummingbird, Google can synthesize that together, your search terms when combined with specific words in your paragraphs might have a totally different meaning.

How Do I Go About Producing Good SEO Copy?

As always, keywords should be included in your copy. Hummingbird and LSI updates did not change the name of that game. However, LSI mitigates the need and pressure to stuff. Google’s LSI updates make it so as a writer, you can be less focused on the keywords, and more focused on producing clean, effortless copy. The best advice is to write naturally, as if you were speaking. Producing and sharing good content will serve you far better than over-engineering your SEO. Engineering is Google’s job. Writing good copy is yours.

How Can I Find Related Terms to Boost My SEO?

There are four easy ways to find LSI keywords:

  1. Google’s related searches feature. You can find LSI keywords by using Google’s related searches. Simply type in your keyword into Google’s search box, and Google will show you what other queries people have searched for. For example, if you type in “Serena Williams,” other people might have searched for “tennis,” and “female tennis players.”
  2. Google’s instant predictions. As you type your query into Google’s search box, the engine will try to guess what you are searching for. Sometimes, these can be valuable keywords to use. Make sure you turn on the Google Instant Search Results feature, though.
  3. Bold words in SERP results. As we know, search engines prioritize some keywords over others. For instance, the page title and heading tags have more traction than keywords stuffed into the body of the text. One way to get around this, though, is to use bold and italics. The search engine still interprets these keywords as more important than the rest.
  4. Keyword research tools. The above three methods are good places to start for your keyword research— they’re cheap, easy, and relatively intuitive to figure out. However, if you really want your page to get SEO traction, Clear Lake’s SEO and marketing services should be your next step. Check out our pricing page to learn more.
About the Author, Michelle Pereira: Michelle is a student at the University of Pennsylvania, and an avid volleyball player.