What is keyword density, and how does it affect SEO?

[btaliat]

For a topic be ranked, and for SEO strategies to be completed, there must be an average number of keyword density. Keyword density, in its simplest role, will give search engine the ability to understand what your website or the particular article is all about.

Keyword density however does not really affect SEO as it used before. Search engine depends more on users' intentions rather than populating articles with keywords, as required by SEO.

What do you notice about this?