Site structure consists of grouping and linking articles on your website. Contextual links are internal links in your site that refer to other pages on your site. To make linking relevant, the current content someone is reading should be related to the page you want to link. Your most important pages are more relevant mostly and they are the ones you end up linking in most pages. The context of your link is important as well as the relevance of the content. Google applies the context of your links to obtain information on the page you are linking. Google has become well informed at realizing related words and concepts by considering information around the link to get details hence highly-ranking your pages if well linked.
For blogs, you should write every single detail on the topics you want Google to rank you for. You should have the main article and sub-topics of the main topic. Then create a link from the main post to the subtopic and from the subtopics to the main post. This way your important pages will have the most links and relevant links.
Contextual linking for online shops
This works differently on online shops with few pages that have informative content. You don’t explore a certain topic on your products since all you do is selling. On product pages, all you focus on is keeping people on your page and convincing them to buy your products. Therefore you should not add contextual links on these product description pages because it might divert your customer after clicking them. To add contextual links you will need to; Link from a bundle product page to individual products, related products or compare with related products, and products frequently bought together.