By relying so much on factors such as keyword density which were exclusively within a webmaster's control, early search engines suffered from abuse and ranking manipulation. To provide better results to their users, search engines had to adapt to ensure their results pages showed the most relevant search results, rather than unrelated pages stuffed with numerous keywords by unscrupulous webmasters. This meant moving away from heavy reliance on term density to a more holistic process for scoring semantic signals.[13] Since the success and popularity of a search engine is determined by its ability to produce the most relevant results to any given search, poor quality or irrelevant search results could lead users to find other search sources. Search engines responded by developing more complex ranking algorithms, taking into account additional factors that were more difficult for webmasters to manipulate. In 2005, an annual conference, AIRWeb, Adversarial Information Retrieval on the Web was created to bring together practitioners and researchers concerned with search engine optimization and related topics.[14]
Now that you’ve set your goals, it’s time to determine the KPIs you need to evaluate whether your content actually hits those goals. There’s no single magic metric that will give you a complete picture of your content success, but a combination of benchmarks can be useful to assess performance. Here’s a guide for choosing the right KPIs according to your goals:
Hey Brian, love your site + content. Really awesome stuff! I have a question about dead link building on Wikipedia. I actually got a “user talk” message from someone moderating a Wikipedia page I replaced a dead link on. They claimed that “Wikipedia uses nofollow tags” so “additions of links to Wikipedia will not alter search engine rankings.” Any thoughts here?
Content gaps – make an inventory of the site’s key content assets, are they lacking any foundational/cornerstone content pieces, non-existent content types, or relevant topic areas that haven’t been covered? What topics or content are missing from your competitors? Can you beat your competitors’ information-rich content assets? Useful guides on Content Gap Analysis:

Smartphone - In this document, "mobile" or “mobile devices" refers to smartphones, such as devices running Android, iPhone, or Windows Phone. Mobile browsers are similar to desktop browsers in that they can render a broad set of the HTML5 specification, although their screen size is smaller and in almost all cases their default orientation is vertical.
Key phrases are keywords containing multiple words. We tend to use the word keyword all the time, but we don’t necessarily mean it’s only one word. ‘WordPress SEO’ is a keyword, as is ‘Google Analytics plugin’. Keywords usually consist of multiple words! So, in this guide, when we talk about keywords, we usually mean a phrase, rather than a single word.
On another note, we recently went through this same process with an entire site redesign.  The executive team demanded we cut out over 75% of the pages on our site because they were useless to the visitor.  It's been 60 days since the launch of the new site and I've been able to still increase rankings, long-tail keywords, and even organic traffic.  It took a little bit of a "cowboy" mentality to get some simple things done (like using 301's instead of blocking the old content with robots.txt!).  I predicted we would lose a lot of our long tail keywords...but we haven't....yet! 

The leading search engines, such as Google, Bing and Yahoo!, use crawlers to find pages for their algorithmic search results. Pages that are linked from other search engine indexed pages do not need to be submitted because they are found automatically. The Yahoo! Directory and DMOZ, two major directories which closed in 2014 and 2017 respectively, both required manual submission and human editorial review.[39] Google offers Google Search Console, for which an XML Sitemap feed can be created and submitted for free to ensure that all pages are found, especially pages that are not discoverable by automatically following links[40] in addition to their URL submission console.[41] Yahoo! formerly operated a paid submission service that guaranteed crawling for a cost per click;[42] however, this practice was discontinued in 2009.
Since heading tags typically make text contained in them larger than normal text on the page, this is a visual cue to users that this text is important and could help them understand something about the type of content underneath the heading text. Multiple heading sizes used in order create a hierarchical structure for your content, making it easier for users to navigate through your document.

A content marketer, for example, can create a series of blog posts that serve to generate leads from a new ebook the business recently created. The company's social media marketer might then help promote these blog posts through paid and organic posts on the business's social media accounts. Perhaps the email marketer creates an email campaign to send those who download the ebook more information on the company. We'll talk more about these specific digital marketers in a minute.