QUOTE: “Supplementary Content contributes to a good user experience on the page, but does not directly help the page achieve it purpose. SC is controlled by webmasters and is an important part of the user experience. One common type of SC is navigation links that allow users to visit other parts of the website. Note that in some cases, content behind tabs may be considered part of the SC of the page. Sometimes the easiest way to identify SC is to look for the parts of the page that are not MC or Ads. ” Google Search Quality Evaluator Guidelines 2019

Comparing your Google Analytics data side by side with the dates of official algorithm updates is useful in diagnosing a site health issue or traffic drop. In the above example, a new client thought it was a switch to HTTPS and server downtime that caused the drop when it was actually the May 6, 2015, Google Quality Algorithm (originally called Phantom 2 in some circles) that caused the sudden drop in organic traffic – and the problem was probably compounded by unnatural linking practices. (This client did eventually receive a penalty for unnatural links when they ignored our advice to clean up).
The above information does not need to feature on every page, more on a clearly accessible page. However – with Google Quality Raters rating web pages on quality based on Expertise, Authority and Trust (see my recent making high-quality websites post) – ANY signal you can send to an algorithm or human reviewer’s eyes that you are a legitimate business is probably a sensible move at this time (if you have nothing to hide, of course).
Everyone knows intent behind the search matters. In e-commerce, intent is somewhat easy to see. B2B or, better yet, healthcare, isn't quite as easy. Matching persona intent to keywords requires a bit more thought. In this video, we'll cover how to find intent modifiers during keyword research, how to organize those modifiers into the search funnel, and how to quickly find unique universal results at different levels of the search funnel to utilize.
QUOTE: “Some Low-quality pages have adequate MC (main content on the page) present, but it is difficult to use the MC due to disruptive, highly distracting, or misleading Ads/SC. Misleading titles can result in a very poor user experience when users click a link only to find that the page does not match their expectations.” Google Search Quality Evaluator Guidelines 2015
Search engine optimization (SEO) is often about making small modifications to parts of your website. When viewed individually, these changes might seem like incremental improvements, but when combined with other optimizations, they could have a noticeable impact on your site's user experience and performance in organic search results. You're likely already familiar with many of the topics in this guide, because they're essential ingredients for any web page, but you may not be making the most out of them.

The SEO starter guide describes much of what your SEO will do for you. Although you don't need to know this guide well yourself if you're hiring a professional to do the work for you, it is useful to be familiar with these techniques, so that you can be aware if an SEO wants to use a technique that is not recommended or, worse, strongly discouraged.