What is the difference between primary and secondary keywords, and how should they be used together?

A primary keyword is the core search term a page targets; secondary keywords include synonyms, variations, and related questions, helping the content address different queries within the same topic. To use them together, first choose a primary keyword that best fits the page’s purpose, then select secondary keywords that share the same search intent and that the content can genuinely address. The goal is focused, comprehensive content—not squeezing every related term into the article.

Primary and secondary describe a keyword’s role on a page, not its length or search volume

A primary keyword is determined by the page’s content and SEO strategy; it is not necessarily the term with the highest search volume. A 2023 Semrush article notes that primary/secondary and short-tail/long-tail are different classifications: a long-tail term can also be a page’s primary keyword.

• The primary keyword defines the focus: What main question does this page answer, or what product information does it provide?
• Secondary keywords help cover related details: What other phrases with similar meanings might readers search for, or what related details might they need?

For example, an article introducing home workouts could focus on “home workouts,” while another specifically covering training without equipment could use “no-equipment home workouts” as its primary keyword. A more specific term is not limited to being a secondary keyword, and secondary keywords are not necessarily broader.

Whether keywords belong on the same page depends on search intent

The principle behind keyword clustering is to address terms with the same search intent on one page, rather than simply grouping terms that look similar. Compare search results for candidate keywords to see whether they offer similar content and address similar needs, then decide which terms to target together.

Secondary keywords do not necessarily all belong on the same page. A 2020 Semrush article used root canal treatment and its cost as an example, suggesting separate pages for related subtopics connected through internal links. Separate pages can cover related subtopics in depth; clustering terms on one page lets that page address queries with the same search intent. Two terms should therefore not automatically be grouped on the same page just because they are related.

Plan the content first, then incorporate keywords naturally

At Procrustes, our content services turn the questions clients genuinely care about into articles, with ongoing planning, writing, and updates.

Once you have chosen your keywords, place them according to the page’s structure rather than setting repetition targets:

• Include the primary keyword in the title tag, main page heading, and opening paragraph to clearly establish the core topic.
• Use secondary keywords in suitable subheadings and body text, ensuring those sections genuinely address the queries.
• If adding a term disrupts the meaning, move it elsewhere or leave it out rather than inserting an unrelated paragraph just to include it.

In 2023, Semrush recommended “one primary keyword and one to five secondary keywords per page,” adding that broader, more in-depth content can accommodate more secondary keywords. This is planning guidance, not a mandatory search engine quota. Including secondary keywords may create more opportunities to appear for related queries, but adding them alone does not guarantee rankings.