SEO guide · updated 30 September 2026

Keyword research for SEO: find and choose the right keywords

Keyword research is finding the words and phrases people type into Google when they look for what you offer, then deciding which page on your site should answer each one. It is the starting point of every SEO campaign.

What are SEO keywords?

SEO keywords are the search terms you want a page to rank for, such as "seo company cape town" or "how long does seo take". They tell you what content to create and how to phrase titles and headings so they match what people search for.

  • Short-tail (head) keywords: one or two words, such as "seo". High volume, very competitive, vague intent.
  • Long-tail keywords: three or more words, such as "affordable seo packages for small business". Lower volume, easier to rank, clearer intent and usually better conversion.
  • Local keywords: include a place or "near me", such as "seo agency Pretoria".
  • Question keywords: "what is", "how to", "why". Great for guides and FAQs.

Search intent: the most important part

Every keyword has an intent, and Google ranks pages that match it:

IntentExampleBest page type
Informationalwhat is local seoGuide or blog post
Commercialbest seo company johannesburgComparison or service page
Transactionalseo packages pricePricing or product page
Navigationalgoogle search console loginThe brand's own page

The easiest way to check intent: search the keyword and look at what already ranks.

How to do keyword research step by step

  1. List seed topics: your services, products, locations and the problems you solve.
  2. Expand them with free sources: Google autocomplete, "People also ask", "Related searches", Google Search Console queries and the Google Ads Keyword Planner.
  3. Check volume and difficulty in a tool such as Google Keyword Planner, Semrush, Ahrefs, Moz or Ubersuggest (see best SEO tools).
  4. Group similar keywords into clusters that one page can answer. "seo company cape town", "cape town seo company" and "seo companies in cape town" belong on one page.
  5. Map each cluster to one page. Two pages targeting the same cluster compete with each other (keyword cannibalisation).
  6. Prioritise by business value, intent and how realistic it is to rank.

How to use keywords on a page

  • Put the main keyword in the title tag, the H1, the URL and the first paragraph.
  • Use related terms and questions naturally in subheadings and body text.
  • Don't repeat the keyword unnaturally. There is no ideal "keyword density"; write for people.
  • Add the keyword to image alt text only where it genuinely describes the image.

Questions answered

How many keywords should I use for SEO?

Give each page one main keyword and a handful of closely related variations and questions, typically 3 to 10. A whole website can target hundreds of keywords across its pages.

How many keywords should a page have?

One primary keyword plus related secondary keywords and questions. If two keywords need different content, they need different pages.

How do I find keywords for my website?

Use Google autocomplete, "People also ask", your Search Console queries and a keyword tool such as Google Keyword Planner. Then check what already ranks to understand intent.

What are long-tail keywords?

Long-tail keywords are longer, more specific searches, such as "seo services for attorneys in Sandton". They have lower volume but less competition and higher conversion rates.

What is keyword density?

Keyword density is how often a keyword appears compared with the total words on a page. Google has no target density; natural, helpful writing matters more.

Is Google Keyword Planner free?

Yes, it is free with a Google Ads account, although it shows ranges rather than exact volumes unless you are running ads.

What is keyword difficulty?

Keyword difficulty is a tool's estimate of how hard it is to rank for a keyword, usually based on the backlinks of pages already ranking. Each tool calculates it differently.

What is search volume?

Search volume is the estimated number of times a keyword is searched per month in a given country.

What is keyword cannibalisation?

Keyword cannibalisation is when several pages on your site target the same keyword and compete with each other, often so that none ranks well.

What are LSI keywords?

"LSI keywords" is a popular term for related words and phrases. Google doesn't use LSI technology, but covering related subtopics naturally helps pages rank.

Where should I put keywords for SEO?

In the title tag, H1, URL, first paragraph, subheadings where natural, meta description and image alt text where relevant.

What is a focus keyword in Yoast SEO?

In Yoast, the focus keyphrase is the main keyword you want a page to rank for; Yoast then checks whether you use it in the title, URL, headings and text.

What are negative keywords?

Negative keywords are a Google Ads setting that stops your ads showing for searches you don't want. They are not used in SEO.

Keep learning

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