Before your content can rank, it needs links. Google finds your posts and pages best when they’re linked to from somewhere on the web. Internal links also connect your content and give Google an idea of the structure of your website. They can establish a hierarchy on your site, allowing you to give the most important pages and posts more link value than other, less valuable, pages. So using the right internal linking strategy can boost your SEO!
Google crawls websites by following links, internal and external, using a bot called Google bot. This bot arrives at the homepage of a website, starts to render the page and follows the first link. By following links Google can work out the relationship between the various pages, posts and other content. This way Google finds out which pages on your site cover similar subject matter.
>> Read : Internal linking for SEO: Why and how ?
Source : Yoast