To be honest, Latent Semantic Indexing is really the “present” of search. If you’ve ever typed in a vague search query praying to find an answer—something like “who was the actor in that movie about the zoo?”—then you’ve experienced Latent Semantic Indexing. (It was Matt Damon, by the way.)
According to Search Engine Journal, "Latent Semantic Indexing (LSI) is a mathematical method used to determine the relationship between terms and concepts in content." That's a bit of a complicated definition. Hubspot does a decent job of simplifying this concept by saying, "In other words, LSI helps search engines identify related keywords and process synonyms to deliver more accurate search results."
What Latent Semantic Indexing means for the future (and present) of search
LSI is Google’s and other search engine’s efforts to continue delivering the best results to search queries.
A brief history lesson
In the early days of search, everything was driven by keywords. You would search for “Matt Damon” and likely receive search results from pages dense with the keyword “Matt Damon”—the denser they were, the better they ranked.
As search engines evolved, they recognized that keyword density wasn’t necessarily a good indicator of quality. Search engines began including a number of other signals to rank search results (domain authority, links, meta information, etc.), but the results were commonly still focused around the keyword or keyphrase.
In more recent iterations of search results, the keyword or keyphrase has taken a back seat to intent. Remember this—intent. Search engines are now focused on delivering the best results based on what a user is looking for, regardless of keyword.
How does Latent Semantic Indexing affect search results?
LSI has played a huge role in the evolution of search results pages. Many Google search results now include answers directly in the search results based on the query the user searched—even if the results don’t contain a single searched keyword. This means users receive better, more relevant search results.
A big driver: voice search
One of the big drivers pushing the LSI movement forward, and also providing an immense amount of data around which to build it, is voice search. With the rapid adoption of Apple’s Siri, Amazon’s Alexa, Google Home, and similar devices, individuals are using voice search more than ever.
Ready for some stats? Google voice search queries in 2016 are 35 times more common than they were 2008 according to Search Engine Watch. 40 percent of adults now use voice search once per day according to Location Day.
This information means that users are asking questions using real language, rather than entering a set of keywords into a search bar. Because of this, the role of LSI is more important than ever and requires search engines to understand and parse voice search queries and their intent to provide quality results.
What does Latent Semantic Indexing mean for marketers?
Google’s admirable longstanding goal has been to connect users with the information they’re seeking in the easiest, fastest, and most effective way (and maybe make a little money on the side). Until recently, that meant sending users to the most applicable web page for what they were looking for.
Now that Google has introduced featured snippets like answers, maps, local packs, shopping results, and the like, users are spending more time in the search results and less time being directed to results pages. In fact, Rand Fishkin of Moz predicted that "the total number of organic clicks Google refers will drop by ~5% by the end of the year [2018]."
Optimizing for Featured Snippets
The challenge above (fewer clicks from Google) creates an opportunity for searchers to engage with your content directly in search results. So how do you do it? Here are some recommendations:
- Focus your content on answering questions. If you have a topic in mind, research which questions are most commonly associated with it, and answer them.
- Ensure that you're doing everything to enhance your local SEO. This includes making sure that you have your Google Business Listings updated.
- Use Google's data highlighter to tag semantic content on your site so that Google can identify exactly what it is.
Optimizing for Latent Semantic Indexing
With search engines using increased amounts of LSI, it's less important to be laser-focused on one or two specific keywords per page. Sure, basing a page around a keyword or keyphrase can be valuable for content planning and basic SEO, but marketers should no longer feel the need to overuse these words in an unnatural way. The emphasis should be on writing natural, quality content that provides the best information on a topic or subject.
Keyword Research for Latent Semantic Indexing
If you’re looking to do some research on a seed topic or keyword, one of our favorite new tools is LSIGraph. This resource uses its own LSI algorithm to provide ideas and opportunities for content creation.
Another one of our favorites is Answer the Public. Answer the Public allows you to enter a keyword or keyphrase. In return, it will provide you with a semantic web of queries and questions related to that topic. I’ve long believed that if you’re able to best answer some of the most common questions about a topic, you’ll have an excellent chance or ranking well for that topic’s related queries. (Warning: You will have to watch an older gentleman in a sweater while you type your search query. Can be hard to explain to co-workers.)
Additional Reading
If you’re looking for some additional resources on Latent Semantic Indexing (LSI), here are a few good ones:
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