Secondary Keywords: What They Are And 3 Ways To Use Them

Most SEO guides talk about picking a primary keyword and building your content around it. That's good advice, but stopping there means you're leaving real ranking potential on the table.

Secondary keywords are where smart content strategy actually lives. They help you cover a topic fully, match what different searchers are looking for, and signal to Google that your page genuinely knows its subject.

This guide breaks down what secondary keywords are, how to find them, and three practical ways to put them to work in your content right now.

Here's the simple version: secondary keywords are the supporting search terms that relate to your main topic without being the central focus of your page.

Your primary keyword is the one phrase your entire piece of content is built around. Secondary keywords are everything else that's closely related. They include synonyms, related phrases, subtopic terms, and questions that people search alongside your main topic.

Think about it this way. If your primary keyword is "email marketing software," your secondary keywords might include things like "best email automation tools," "email marketing for small businesses," "how to build an email list," and "email campaign analytics." These aren't competing with your main keyword. They're supporting it.

Secondary Keywords vs. Primary Keywords

The difference isn't just about importance. It's about role.

Your primary keyword defines the topic of your page. It's what you've chosen to rank for above everything else. Secondary keywords fill in the gaps around that topic. They help your content feel complete rather than one-dimensional.

Here's a quick way to think about it:

• Primary keyword: The one phrase your page is centered on
• Secondary keywords: The supporting terms that expand coverage of that topic
• Usage: Primary goes in your title, URL, and opening paragraph. Secondary keywords go in headings, body copy, and image alt text.
• Volume: Primary keywords often have higher search volume. Secondary keywords are often lower volume but more specific.

Both matter, but they do different jobs.

Secondary Keywords vs. LSI Keywords

You've probably heard the term "LSI keywords" thrown around in SEO circles. LSI stands for Latent Semantic Indexing, and it's become a bit of a buzzword that gets misused constantly.

True LSI keywords come from a specific mathematical model that Google doesn't actually use the way the SEO industry implies. Real talk: the term "LSI keywords" in modern SEO mostly just means "semantically related keywords," which is basically another way of describing secondary keywords.

For practical purposes, don't get too caught up in the distinction. Whether you call them LSI keywords, related keywords, supporting keywords, or secondary keywords, the idea is the same: use terms that are conceptually connected to your main topic so your content covers it properly.

Secondary keywords is the more accurate and useful term for what you're actually trying to do.

Why Secondary Keywords Matter in 2026

Search engines have gotten really good at understanding context. Google's algorithms don't just match exact phrases anymore. They look at the full picture of what a page is about.

That shift changes how you should write. A page that only repeats its primary keyword over and over actually looks thin compared to a page that covers the topic from multiple angles using varied, related language.

Secondary keywords also help you rank for more than one search query. It's not unusual for a well-written article to appear in results for dozens of slightly different searches. Each secondary keyword you include is a potential additional ranking opportunity, and in 2026, with AI-generated content flooding the web, the pages that win are the ones that demonstrate real depth and breadth on a topic. Secondary keywords are part of how you show that.

Finding good secondary keywords doesn't have to be complicated. You've got several solid options depending on how much time you want to spend and what tools you have access to.

Start With Your Primary Keyword

Your primary keyword is your starting point for everything. Once you've got it locked in, ask yourself:

• What questions do people ask about this topic?
• What related problems are searchers trying to solve?
• What subtopics would a reader expect to find covered?
• What terms would someone use if they didn't know the exact phrase?

Jot down every variation you can think of. Don't filter yet. Just brainstorm. You can narrow it down later.

Use Search Engine Results Pages

Google hands you secondary keyword ideas for free. Seriously. You just have to know where to look.

Search your primary keyword and check these spots on the results page:

1. "People Also Ask" boxes - these are gold. Each question is a potential secondary keyword or H3 heading.
2. Related searches at the bottom of the page - Google's own suggestions based on what people search after your term.
3. Autocomplete suggestions - start typing your keyword and see what Google fills in.
4. Featured snippet content - the phrases used in featured snippets often reflect how people phrase their searches.

Spend ten minutes doing this for any article you're planning and you'll have more secondary keywords than you need.

Try Keyword Research Tools

If you want more data, keyword research tools give you search volumes, difficulty scores, and related term lists that go much deeper than manual searching.

Tools like Semly Pro, Semrush, Ahrefs, and Surfer SEO all let you plug in a primary keyword and pull up lists of related terms. You can filter by search volume, look at what terms competing pages rank for, and spot gaps in your current content.

The key is not to get buried in data. You don't need 200 secondary keywords. You need 5 to 10 that genuinely fit your content and cover the topic angles your readers actually care about.

This is probably the most direct way to put secondary keywords to work. Instead of treating them as extras you sprinkle in after writing, use them to plan your content structure from the start.

Here's why this matters: when Google reads your page, it pays close attention to your headings. H2s and H3s signal what each section covers. If your headings contain secondary keywords, you're giving search engines a clear map of your content's full scope.

Map Secondary Keywords to Headings

Before you write a single word of body copy, look at your list of secondary keywords and ask: which of these could become a section heading?

Let's say you're writing about "project management software." Your secondary keywords might include phrases like "how to track team tasks," "project management for remote teams," "free project management tools," and "kanban vs. Gantt charts." Each of those could anchor an H2 or H3 section.

Your article outline practically writes itself, and each section naturally brings in the keyword it's built around without forced repetition.

This approach does two things at once. It improves your content's readability for humans, and it gives search engines clear keyword signals throughout the page. Win-win.

Cover Subtopics Your Readers Expect

Think about what happens when someone reads a piece of content and feels like something's missing. They leave. They go find a more complete source. That's a signal to Google that your page didn't satisfy the searcher.

Secondary keywords tell you what readers expect to find. If you're writing about "how to start a podcast," and secondary keywords include "podcast equipment for beginners," "how to edit podcast audio," and "how to submit a podcast to Spotify," those aren't optional extras. They're what your audience needs to feel like they got a complete answer.

Use your secondary keywords as a checklist. If a term shows up in your research and you haven't covered that angle, you've found a gap to fill.

Avoid Keyword Stuffing

Here's the flip side: don't force it.

Secondary keywords should appear naturally in your content. If you're bending sentences into awkward shapes to fit a phrase in, it's probably not the right place for it. Readers notice when writing feels stuffed, and so do search engines.

A good rule of thumb: if you wouldn't say it out loud in normal conversation, don't write it. Your secondary keywords should feel like they belong where you've put them, not like they were inserted after the fact.

Quality beats quantity every time. Five well-placed secondary keywords do more than twenty forced ones.

Search intent is one of the most talked-about concepts in SEO right now, and for good reason. Google's whole job is to give people what they're actually looking for, not just what they literally typed. Secondary keywords are a big part of how you align your content with what searchers really want.

Different Searchers, Different Phrases

Two people can be looking for the exact same thing and phrase their searches completely differently.

Someone might search "how to lose weight fast," while another person searches "quick ways to drop pounds," and a third types "diet tips that actually work." They all want the same outcome, but if your content only optimizes for one of those phrases, you're invisible to the other two searchers.

Secondary keywords let you speak to all of them at once. By covering the topic with varied, natural language that includes these related phrases, you catch searchers who wouldn't have found you otherwise.

This is especially true for informational content. People searching to learn something phrase their questions in dozens of different ways. The more of those natural variations you include, the wider your reach.

Matching Keywords to Content Sections

Not every secondary keyword fits every part of your article. Some belong in the introduction, some in body sections, and some work best in your conclusion or FAQ.

Here's a practical approach:

• Introductory paragraphs: Use secondary keywords that frame the problem or question your content addresses
• Body sections: Use secondary keywords that match the specific subtopic of each section
• FAQ sections: These are perfect for long-tail secondary keywords phrased as questions
• Conclusions: Use secondary keywords that reinforce your main message and call to action

When you match keywords to the right sections, your content feels natural and purposeful. Each part of the page does its own keyword job without the whole thing feeling like it was written for a bot.

How This Boosts Your Rankings

There's a compounding effect here that's worth understanding.

When your page ranks for one secondary keyword and people click, read, and don't immediately bounce, that's a positive signal to Google. When the same happens for five secondary keywords, those signals stack up. Your page builds authority not just for your primary keyword, but for the broader topic area.

Over time, pages that do this well tend to rank higher for their primary keyword too. It's not a coincidence. Search engines reward pages that genuinely cover a topic well, and secondary keyword coverage is a major part of what "covering a topic well" actually looks like in practice.

You're not just chasing extra rankings. You're building a stronger page overall.

Internal linking often gets treated as an afterthought. Drop a few links in, call it done, but when you tie your internal link strategy to your secondary keywords, the whole thing gets a lot more powerful.

Here's the idea: your secondary keywords reveal the subtopics within your content. Those subtopics are natural bridges to other pages on your site that cover those angles in more depth, and when you link between pages using keyword-relevant anchor text, you're passing both link authority and topical relevance signals.

Anchor Text and Keyword Relevance

Anchor text is the clickable words in a link. When you link from one page to another, the anchor text tells search engines what the destination page is about.

If you're writing an article about content marketing and you mention "keyword research," that phrase is a natural secondary keyword. It's also a natural anchor for linking to your dedicated keyword research guide. You've just used a secondary keyword to create a relevant, helpful internal link with descriptive anchor text.

Compare that to linking with "click here" or "read more." Those tell search engines nothing. Keyword-based anchor text tells them exactly what the linked page is about.

The result: both pages get a small authority boost, and search engines understand your site's topic structure better.

Build Topic Clusters With Secondary Keywords

Topic clusters are one of the strongest content strategies going in 2026. The idea is simple: you have a main "pillar" page on a broad topic, and several supporting "cluster" pages that cover subtopics in more depth. Each cluster page links back to the pillar, and the pillar links out to the clusters.

Secondary keywords are basically a map to your cluster content.

If your pillar page is about "social media marketing," your secondary keywords might include "Instagram marketing tips," "social media content calendar," "how to grow a Twitter following," and "social media analytics tools." Each of those secondary keywords could be its own cluster page, linked from the pillar.

This creates a tight, well-connected content structure that search engines love. Your pillar page ranks better because it's supported by depth. Your cluster pages rank better because they're connected to a strong authority hub.

Keep Your Link Structure Clean

One thing to watch: don't link to the same page from the same article multiple times using slightly different anchor text. That gets messy and looks spammy.

Pick the most relevant secondary keyword as your anchor text and use it once, cleanly. If you want to mention the topic again later in the piece, you can do so without adding another link.

Also, only link where it genuinely adds value for the reader. If someone would realistically want to follow that link to learn more, include it. If you're only adding it for SEO, the reader experience suffers, and that's never worth it.

Finding and using secondary keywords manually is doable, but if you're producing content at scale, or if you want a faster, more data-driven process, a dedicated tool makes a real difference. Semly Pro was built specifically for this kind of work.

How Semly Pro Helps You Find and Use Secondary Keywords

Semly Pro combines AI-powered content generation with keyword tracking and competitive analysis. That means you're not just getting keyword suggestions. You're getting content that's already built around the right secondary keywords for your topic.

Here's what you get with each plan:

• Pro (€139/mo): 40 long-form SEO articles per month, 25 AI tracking prompts, 1 project, AI visibility score and competitor detection. Good for solo marketers and small teams who want consistent content output without the manual legwork.
• Business Pro (€229/mo): 100 long-form SEO articles per month, 50 AI tracking prompts, 3 projects, advanced AI metrics, LLMs. txt generation, data export in CSV and JSON, roles and permissions, and priority support. Built for agencies and growing teams managing multiple clients or content streams.
• Managed SEO (€469/mo): Everything in Business Pro, plus a dedicated Semly Pro-trained SEO strategist who runs everything for you. Articles are researched, written, and published by the team. AI visibility tracking runs weekly across ChatGPT, Perplexity, and Google AIO. Schema and LLMs. txt optimization is handled for you. You also get monthly strategy and performance review calls plus a priority Slack channel.

If you need more capacity on any tier, you can add article packs, AI prompt packs, extra projects, or extra team seats without upgrading your full plan. The 25 Article Pack is €55/mo, the 10 Article Pack is €27/mo, and an AI Prompt Pack is €36/mo.

All plans come with a 7-day free trial. No commitment needed to get started.

Semly Pro vs. Other SEO Tools

How does Semly Pro stack up against the other tools you might already be using? Here's an honest look:

The big differentiator with Semly Pro isn't just keyword research. It's the combination of content creation, AI visibility tracking, and the managed service option. Most tools do one or two of these things. Semly Pro does all of them in one place.

You've found a bunch of secondary keywords. Now you need to decide which ones to actually use. Not every keyword that's related to your topic deserves a spot in your article.

Check Search Volume and Difficulty

Search volume tells you how many people are actually searching for a term. Difficulty tells you how hard it is to rank for it.

For secondary keywords, you generally want:

• Moderate search volume (high enough to matter, low enough that you can realistically compete)
• Lower difficulty than your primary keyword
• Clear relevance to your topic, not just surface-level connection

A secondary keyword with 200 monthly searches that's directly relevant to your topic is worth more than one with 2,000 searches that's only loosely connected.

Look for Contextual Relevance

This is the test that matters most.

Ask yourself: if a reader is already interested in my primary keyword, would they also care about this secondary keyword? If the answer is yes, it belongs. If you're not sure, it probably doesn't.

Contextual relevance also means the secondary keyword fits naturally into your content's voice and flow. If including it requires a jarring tangent or a forced section that doesn't fit the rest of the article, leave it out. Save it for a different piece of content where it actually belongs.

Prioritize Keywords That Match Your Goals

Different secondary keywords serve different purposes. Some drive traffic. Some improve depth. Some help with internal linking. Some do all three.

Know what you're trying to accomplish with each piece of content before you pick your secondary keywords. If you're writing a commercial page aimed at conversions, lean toward secondary keywords with transactional intent. If you're writing an informational guide, prioritize secondary keywords that cover the topic broadly and answer common questions.

Your goals should shape your keyword choices, not the other way around.

Bottom line: good secondary keyword selection is about quality and fit, not volume. Ten well-chosen keywords beat fifty random ones every single time.

What are secondary keywords in SEO?

Secondary keywords in SEO are supporting search terms that relate to your primary keyword. They include synonyms, related phrases, subtopics, and question-based terms that help search engines understand the full scope of your content and help you rank for more than one search query.

How many secondary keywords should I use per article?

Most SEO professionals recommend 5 to 10 secondary keywords per article, depending on the length and depth of the content. For a standard 1,500-word piece, 5 to 7 secondary keywords is plenty. For longer, more detailed guides like this one, you can go up to 10 without it feeling forced.

Where should I place secondary keywords in my content?

Secondary keywords work best when placed in H2 and H3 headings, early body paragraphs within relevant sections, image alt text, FAQ sections, and the meta description. Don't force them all into the opening paragraph. Spread them naturally throughout the piece based on where they fit best contextually.

Do secondary keywords help with ranking?

Yes. Secondary keywords help your page rank for a broader set of search queries rather than just your primary keyword. Over time, ranking for multiple related terms builds your page's authority and can indirectly improve your primary keyword rankings too, since search engines see your page as a thorough resource on the topic.

What's the difference between secondary keywords and long-tail keywords?

Long-tail keywords are specific, lower-volume phrases that often contain three or more words and have a clear, narrow intent. Secondary keywords is a broader category that includes long-tail terms but also covers synonyms, related phrases, and subtopic terms regardless of length. Many long-tail keywords are also secondary keywords, but not all secondary keywords are long-tail.

Can I use the same secondary keywords on multiple pages of my site?

It depends. If two pages are covering genuinely different aspects of a topic, some keyword overlap is fine and even expected, but if two pages are directly competing for the same primary keyword and the same secondary keywords, you've got a keyword cannibalization problem. Use Semly Pro or another SEO tool to audit for cannibalization and differentiate your pages clearly.

How are secondary keywords different from LSI keywords?

LSI stands for Latent Semantic Indexing, a term that gets misused often in SEO. True LSI comes from an older mathematical model, and Google doesn't work the way most "LSI keyword" advice implies. in practice, what people call LSI keywords are simply semantically related terms, which is essentially what secondary keywords are. The term "secondary keywords" is more accurate and more useful for practical content strategy.

Should secondary keywords appear in my title tag?

Your title tag should be built primarily around your primary keyword. That said, if a secondary keyword fits naturally into your title and makes it more descriptive or compelling, including it is fine. Don't stuff multiple keywords into a title just to cover more ground. Keep your title readable and focused, and let secondary keywords do their job in the body of the page.

How does Semly Pro help with secondary keywords?

Semly Pro's AI content generation is built around producing SEO-optimized long-form content that naturally incorporates primary and secondary keywords. The platform also includes competitor detection and AI visibility tracking, so you can see which keywords your competitors are ranking for and spot opportunities you might be missing. Plans start at €139/mo, and there's a 7-day free trial to get started without committing.

How often should I update content to include new secondary keywords?

A content audit every three to six months is a good habit. Search trends shift, new questions emerge, and "People Also Ask" boxes change. When you revisit older articles, check whether new secondary keyword opportunities have appeared and whether your existing secondary keywords are still performing. Adding a new relevant section or updating headings to reflect current search behavior can give older content a meaningful rankings boost.