Digital PR: An introduction to writer/blogger outreach

Regardless of whether a website is a personal blog or a media outlet that employs paid journalists, if it is perceived as an authoritative site that can be trusted, and has an expert voice on the topic, a link from it can be valuable for both ranking and brand awareness. The benefit here is that the receiving site is effectively getting an endorsement. If an individual follows and trusts a writer and sees a link from them to another website, they are more likely to trust that link.
The disciplines of content marketing and SEO are intertwined. Generally speaking, content marketing concerns the creation and publication of content to engage an audience, while SEO concerns the research of topics being searched for by people using Google (or other search engines). Both content marketers and SEOs will also have a focus on creating link-worthy content as this demonstrates value, quality and trust.
So, why do writers link and how should marketers plan their outreach to these writers?