Keyword frequency
Keyword frequency is simply the number of times a word or phrase appears on a page. Repeating the main subject naturally can help make the page clear, but repetition alone does not create relevance. A useful page normally includes the language customers use alongside related services, problems, places and questions.
Keyword density
Keyword density expresses that repetition as a percentage of the total word count. It is not a sensible target for modern content. Writing to reach an arbitrary percentage usually makes copy repetitive and less persuasive. The better test is whether the page answers the search properly and reads naturally to a prospective customer.
Keyword difficulty
Keyword difficulty is an estimate—usually supplied by an SEO tool—of how competitive a search result may be. Different tools calculate it differently, so it should be treated as comparative guidance rather than a fact. Commercial relevance, local competition, the strength of the current website and the quality of competing pages matter more than one score.
Keyword proximity
Keyword proximity describes how closely related words appear to one another. Clear phrases such as “website design in Durham” are easier to interpret than the same words scattered without purpose. That does not mean every phrase must be forced into an exact order; headings, context and the overall meaning of the page all help search engines and readers understand it.
What should a small business do?
Choose a clear primary subject for each important page. Use the customer’s language naturally, cover the questions needed to make a decision, add specific proof and connect related pages with useful internal links. Measure whether the page gains relevant visibility and enquiries—not whether a phrase has reached a supposedly perfect density.