Keyword Clustering

I wrote this post in Spanish in 2021 and adapted it to English in 2026.

Warning: this post has valuable information if you like semantic SEO. If you don't, go read another post in the SEO section of my blog, because you'll get bored with this content about keyword clustering and the right way to organize content logically for any SEO niche.

Seriously, though: this post on keyword clustering is condensed so anyone can get something out of it and enjoy it, but if creating content isn't your thing, there are better SEO posts on my blog you might like.

If you love creating quality content, you'll be fascinated by this post. I won't drag out the intro any longer: let the party begin.

What Is Keyword Clustering? #

A "cluster" is a bunch or a group, so "clustering" is the act of grouping.

So keyword clustering means we're grouping keywords that, to us, seem to be related in some way.

What Kind of Relationship Can Two Keywords Have to Belong in the Same Keyword Cluster? #

The truth is, two keywords can be related beyond repeating the main keyword inside them (keyword variations, long tail, etc.). Simply belonging to the same semantic group is enough to group them together.

In general (careful, this is how I do it), you can group keywords by two kinds of affinity: semantic, and keyword variation. I'll explain a bit more about what I mean, and I'll give a couple of examples to show it all in context.

Keyword clustering by semantic affinity

Semantics is just a branch of linguistics that studies how words relate to each other. That's a real challenge, because the same word can mean different things.

Example: plant.

Rice plant? Rice processing plant?

A rice plant is a living, photosynthetic thing, while a rice processing plant is an industrial plant (a factory, basically), so the two keywords (the phrases that contain "plant") are different.

Sure, they're different if the seed keyword is "plant". But what if I decide the seed keyword I'm using is "rice"?

In that case, the two keywords "rice plant" and "rice processing plant" now have a close semantic relationship: rice production.

On top of that, both become variations of the keyword "rice", so they can both live inside a niche about the rice production process, from the seed all the way to the end consumer.

Another example?

Sure. Semantic SEO specializes in grouping keywords (keyword clustering) using any kind of semantic affinity between them, to build a niche with a logical structure (at the semantic level).

Example: means of transportation

Bicycle, car, airplane, donkey.

They're all different keywords, but since they share the semantic relationship "means of transportation", they can all live together in one niche without any problem.

Example for an Amazon mega niche: kitchen

Coffee maker, hand mixer, blender.

Each of these keywords is different, and you could create a specific micro niche for each one. In this example, the mega niche's theme is "kitchen", so the semantic affinity of those keywords is that they're all tools you find in a kitchen.

What happens if you have a coffee maker micro niche and you want to add a section for hand mixers?

You screw it up. Period.

You screw up the niche because, even though they share the semantic affinity "kitchen", they have no direct relationship at the keyword level, and since it's a micro niche you won't have room to create enough content to become "the go-to site for coffee makers and hand mixers".

Semantic affinity for keyword clustering should be built in three phases:

• Semantic keyword clustering, phase 1: the general semantic affinity of the niche. Example: coffee makers.
• Semantic keyword clustering, phase 2: the semantic affinity of the categories (sections of the website). Example: types, pods, brands.
• Semantic keyword clustering, phase 3: the semantic affinity of each post (every article on the website). Example: "dolce gusto coffee makers" and "dolce gusto coffee makers models and prices" belong in the same post, under /brands/dolce-gusto-coffee-makers. But "dolce gusto coffee maker pods" and "dolce gusto pod flavors" belong in a different post, under /pods/dolce-gusto-coffee-maker-pods.

Why did I keep "coffee makers" and "pods" in the URLs? To keep a logical structure. Otherwise both slugs would be /dolce-gusto/, and only the category silo would change, creating a massive screwup at the URL architecture level. But don't sweat it: I already wrote a post about that, and you can read it here: silo URL architecture for SEO niches.

Let's get back to what we're here for, keyword clustering, because we still need affinity by keyword variation.

Keyword clustering by keyword variation affinity

By this point in the post, I'm guessing you already have an idea of where I'm going with this, but let me clear up any doubts by explaining what I mean by affinity through keyword variation.

Say you have a seed keyword, for example: coffee maker.

It will have its own variations, something that looks like: keyword + whatchamacallit.

That includes the plural of the keyword and every possible combination. But you already know how to group them, right? Using the semantic affinity from the previous section, you can already build a pretty logical map of which keywords belong to the niche, which ones are categories and which ones are posts.

I use this keyword variation affinity at the heading level inside a post, that is: keyword clustering at the level of the H headings (H2, H3, H4).

It's the direct continuation of the logic from the previous step. Let's look at an example for a post called: free fire drawings

Main keyword: free fire drawings (H1)
  Secondary keyword: pixel art free fire drawings (H2)
    pixel art free fire character drawings (H3)
    pixel art free fire gun drawings (H3)

All those keywords share the semantic affinity "free fire drawings" and had already been picked to go in the same post. But how do you group them inside the post? This is where grouping by keyword variation affinity comes in handy.

In this particular example, "pixel art" would be the seed keyword that generates:

• pixel art free fire drawings
• pixel art free fire character drawings
• pixel art free fire gun drawings

So they all go under the same H2, as a cluster inside the "post" keyword cluster, which in turn sits inside the "category" keyword cluster, which sits inside the "niche" keyword cluster.

The big mistake here is clustering by keyword variation affinity first, because, going back to the coffee maker example, you'd end up putting the "dolce gusto coffee maker pods" keywords inside "dolce gusto coffee makers", and I already showed you why they belong in two different posts under two different categories.

I bet you're already in love with keyword clustering... and who wouldn't be, it's that cool, right? But not everything that glitters is gold, so I'll show you a few pros and cons of this whole keyword clustering thing (at least the ones I see).

Pros and Cons of Keyword Clustering #

Pros of keyword clustering

First of all, there's the site's vertical focus: in Google's eyes, you're more specific about one particular topic, so your website looks like an expert's.

Anything else?

How well you end up using your link juice. It doesn't matter if the first thing you manage to rank is a keyword with 10 searches a month: it'll start sending strength to the whole website, drip by drip, and so on.

Finally, there's organization, and not just for Google optimization. Content creation becomes more organized: you can prioritize expanding (content-wise) a category that's performing better on the site, to ride the boost it's getting (whether from algorithm changes or whatever), instead of publishing blind.

Cons of keyword clustering

Now for the downsides of this technique, and for me there aren't any. Rather than a downside, the only thing I'd call it is a hassle.

Which one?

The time you spend sorting keywords until you have the website's full structure with every cluster well defined.

Obviously, you can ease that a bit by writing a script (or leaning on Excel if you're not handy with code) that organizes the keywords for you. That's why I say it's less than a downside: it's a hassle.

Final Summary #

Keyword clustering is an effective, efficient technique for organizing your content with a logical structure.

I think every good SEO project should have keyword clustering as a key first step.

However, because of all the time it takes, it could backfire if you want to go after niches on different topics, where you'll have to learn the semantic affinities of each one.

If you stick to one niche (mastering its semantic affinity more and more), this technique can take you to the top of the SERPs without leaning on too many links.