What are LSI Keywords?
LSI (Latent Semantic Indexing) Keywords are semantically related terms that search engines use to deeply understand content on a webpage.
Why are LSI Keywords Important?
In the early days of SEO, Google and other search engines would figure out a page’s topic based 100% on the keywords they found on the page.
So if Google saw the keyword “Content Marketing” over and over again, they’d say: “This page is obviously about content marketing”.
That’s why keyword density was so important back in the day.
If you didn’t use your keyword bunch of times, Google wouldn’t understand that your page was about that term.
Fast forward to today, and Google is MUCH smarter.
Today, Google’s goal is to figure out a page’s overall topic.
And Google relies on LSI keywords to understand content at such a deep level.
For example, let’s say you just published a blog post about cold brew coffee.
Google will still scan your page to see if you use the term “cold brew coffee” in your title tag, content, image alt text, etc.
But they’ll also scan your page for LSI keywords (like “filter”, “temperature”, “grind”, “cold water”, and “ice”).
And when they see these LSI keywords in your content, they’ll say: “We’re confident that this page is about the topic of cold brew coffee.”
In fact, a recent Google research paper states that they use “words frequently occurring together” to understand an article’s main topic:
One thing I should point out:
LSI Keywords are NOT synonyms.
Instead, they’re terms that are closely tied to your target keyword.
For example, take a word like: “jogging”.
Well, “running” is just a synonym of “jogging”.
There’s nothing wrong with using that synonym in your article (in fact, it can help with your on-page SEO).
But it’s not an LSI Keyword.
LSI keywords for “jogging” are things like: “shoes”, “cardio” and “5k”.
With that, here’s how to find LSI keywords.
Google Autocomplete is one of the fastest and easiest ways to uncover LSI terms to use in your content.
For example, I recently published “The Ultimate SEO Site Audit”.
And to optimize that page, I typed “SEO Audit” into Google.
And paid attention to the bold words that it suggested to me.
These bold words are LSI Keywords.
After all, they’re terms that human users search for when they search for anything related to “SEO Audit”.
So I included those terms in my content:
Both of these tools give you A LOT more suggested keywords than doing things the old-fashioned way.
That said, Google tends to suggest the most popular (and therefore most relevant) terms right off the bat.
So I usually only use one of these tools if I want to optimize my content to the max.
LSIGraph and LSIKeywords.com
They both work pretty much the same way.
You type in a keyword that you want to rank for…
…and get a list of LSI terms that you can include in your content.
They’re both free SEO tools. So you can’t go wrong with trying out both of them.
(Although I should point out that LSIGraph does have a paid plan… so it’s technically “Freemium”)
Overall, I think both tools work great. But if I had to pick one, I’d have to go with LSIKeywords.com.
It tends to give me more closely related terms that aren’t straight up variations of my target keyword.
For example, when I type “SEO tools” into LSIKeywords.com, I get tons of related terms (like “Google Analytics”) that make PERFECT LSI keywords.
“Searches Related to…”
“Searches Related to…” is similar to Google Autocomplete.
But instead of Google suggesting keywords as you search, they give you related terms at the bottom of the search results.
For example, this list of SEO tools is one of my high-priority pages:
And considering how insanely competitive this keyword is, I know that I need to nail my LSI… or I have little to no chance of rankings.
That’s why I searched for “SEO Tools” and scrolled down to the bottom of the page.
Then, I identified bold terms that made sense for my post.
And included those in my content:
Simple, yet effective.
Bold Terms in Google Snippet Descriptions
This is another way to find LSI Keywords directly from Google.
You might have noticed that Google bolds terms in result snippets that match your keyword:
And if you look closely, you’ll notice something else:
Google doesn’t ONLY bold terms that exactly match what you just searched for.
They also bold words and phrases that are similar.
For example, let’s look at the results when you search for “PC Repair:
Yes, Google bolds the exact term:
But they also bold related terms, like “Computer Repair” and “PC Fix”:
Needless to say, these are LSI keywords that you want to sprinkle into your content.
Google Correlate is a long-forgotten tool that Google hasn’t been updated in years.
In fact, the copyright in the page footer still says “© 2011 Google” 🙂
This tool might look dated, but it’s still straight from Google. So you know that the info that you get is pretty darn reliable.
Google Correlate is different than the other tools I’ve talked about so far. So it doesn’t generate topically-related terms.
Instead, Google Correlate generates keywords that people also search for around the time that they search for your target keyword.
For example, let’s say your keyword is “low carb diet”.
Well, when you put “low carb diet” into Google Correlate, you get these results:
This makes sense. Anyone interested in the low carb diet is also probably on the hunt for things like “low carb snacks”.
The only thing to keep in mind about Google Correlate is that you can get some funky results.
Just ignore these and focus on terms that make sense for your content.
Google Keyword Planner
As it turns out, the Google Keyword Planner is also an LSI Keyword MACHINE.
For example, if you put “SEO Tools” into the GKP, you get a list of “Keyword ideas”:
Some of these will be synonyms and variations of your keyword:
But if you dig deep, you can find some sweet LSI phrases that you’d be hard pressed to get any other way:
Pro Tip: you don’t need to enter a keyword into the GKP. You can also use a landing page.
Specifically, you can use a competitor’s landing page that’s ranking above you in the search results.
When you do, Google will scan the page and spit out keywords that they consider relevant to that page’s topic.
(In other words: LSI Keywords)
Google Image Tags
This is a new feature inside of Google Images that I don’t see a lot of people talk about.
And it’s an LSI goldmine.
To use it, just pop your keyword into Google images.
And Google will hook you up with a bunch of related terms above the image results:
You can do the same thing with Pinterest (in fact, this is where I first saw this feature used).
But these suggestions don’t come from Google. So now I stick with Google Images.
Use LSI Keywords Throughout Your Article
Now that you have a list of LSI Keywords, how do you use them?
I’ve tested this quite a bit.
And my takeaway is: it doesn’t really matter.
In my experience, as long as Google sees these terms somewhere on your page, you’re good.
So feel free to include your LSI terms:
- In your title tag
- In image alt text
- As a H2 or H3 subheader
- In your H1
- In the content itself
For example, I published this guide to learning SEO a few months ago:
And one of the “Searches related to…” keywords that I found was: “basics”.
So I included that term in my content a few times:
That’s all there is to it.
Semantic SEO: Everything you need to know about Google Hummingbird and Semantic SEO.
How to do “Semantic SEO” in 8 Minutes: A very actionable video that demonstrates a lot of the techniques I’ve outlined here.
Latent semantic analysis: Wikipedia entry dedicated to some of the technology behind LSI. Super dense but worth reading if you want to understand the “why” behind LSI keywords.