Link diversity

A link building strategy where you try to collect an array of links from different types of websites (blogs, news, directories, social media) and different domains (.com, .edu) with various anchor text, as well as having both “nofollow” and “do follow” links.

Not all SEO experts agree that this is important, but it does give a signal of a natural link profile where a certain type of link isn’t being represented more than the other.