Keyword density, also known as keyword density, is an essential aspect of search engine optimisation (SEO). This metric indicates how often a particular keyword or phrase appears in relation to the overall text on a web page. Finding an optimal balance is crucial to appealing to both search engines and readers.

Achieving the right density is an art. Too frequent repetition of a word can be seen as "keyword stuffing", which can have a negative impact on rankings. On the other hand, too low a density can result in the content not ranking well for the relevant search queries. The recommended keyword density varies, but is often in the range of 1-2%. This makes it possible to create content that is natural and relevant for both readers and search engines.

In addition to simply counting keywords, it is also important to use synonyms and related terms. This approach, known as Latent Semantic Indexing (LSI), helps to reinforce the context and relevance of the content for search engines. LSI helps to ensure that a page ranks not only for a specific keyword, but for a whole range of topics.

Good SEO copy flows naturally and provides value to the reader while incorporating relevant keywords and related phrases. It's about finding a balance between optimising for search engines and creating engaging, informative content for the reader. Ultimately, the user experience is the most important thing, and quality content that engages and informs the reader will always be a core goal of SEO.