Co-occurrence is a type of search engine optimisation, which tells how closely and frequently related keywords would occur on a single webpage or on many. This concept puts a contextual relationship between the words that would describe their relevance to satisfying their search queries when search engines want to improve content for them. For example, if “SEO optimisation” is found frequently on the same page as “search engine ranking,” this tells Google there is a semantic relevance for indexing both of those terms. It might not be as direct about an external link, but it is an indirect method that co-occurrence handles semantic SEO to give pages authority and visibility in search results using natural language-based association.