Google is a link-based search engine. Google doesn’t need content to rank pages but it needs content to give to users. Google needs to find content and it finds content by following links just like you do when clicking on a link. So you need first to make sure you tell the world about your site so other sites link to yours. Don’t worry about reciprocating to more powerful sites or even real sites – I think this adds to your domain authority – which is better to have than ranking for just a few narrow key terms.

QUOTE: “Supplementary Content contributes to a good user experience on the page, but does not directly help the page achieve its purpose. SC is created by Webmasters and is an important part of the user experience. One common type of SC is navigation links which 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.” Google Search Quality Evaluator Guidelines 2017
Google will INDEX perhaps 1000s of characters in a title… but I don’t think anyone knows exactly how many characters or words Google will count AS a TITLE TAG when determining RELEVANCE OF A DOCUMENT for ranking purposes. It is a very hard thing to try to isolate accurately with all the testing and obfuscation Google uses to hide it’s ‘secret sauce’. I have had ranking success with longer titles – much longer titles. Google certainly reads ALL the words in your page title (unless you are spamming it silly, of course).
Mike Levin is the Senior SEO Director at Ziff Davis, PCMag's parent company. His career goes back 25 years to the halls of Commodore Computers, as an original Amiga fanboy to be beamed up by the mothership just as it imploded. Over his past 10 years in NYC, Mike's highlights have included leading the Apple Store, Kraft and JCPenney SEO accounts whi... See Full Bio
Google used to make much of its ad hoc keyword search functionality available as well, but now the Keyword Planner is behind a paywall in AdWords as a premium feature. Difficulty scores are inspired by the way Google calculates its Competition Score metric in AdWords, though most vendors calculate difficulty using PA and DA numbers correlated with search engine positions, without AdWords data blended in at all. Search Volume is a different matter, and is almost always directly lifted from AdWords. Not to mention keyword suggestions and related keywords data, which in many tools come from Google's Suggest and Autocomplete application programming interfaces (APIs).

Google and Bing use a crawler (Googlebot and Bingbot) that spiders the web looking for new links to find. These bots might find a link to your homepage somewhere on the web and then crawl and index the pages of your site if all your pages are linked together. If your website has an XML sitemap, for instance, Google will use that to include that content in its index. An XML sitemap is INCLUSIVE, not EXCLUSIVE.  Google will crawl and index every single page on your site – even pages out with an XML sitemap.

Taboola (like many websites) would benefit from iterative SEO, meaning its team should make distinct revisions to the SEO page titles, content headers, and other text to see whether rankings improve without hurting their top positions. But they shouldn’t make too many changes at one time or they won’t know what worked and could disrupt rankings. They could monitor rankings after testing keyword-placement scenarios. (Most website pages are indexed within days or a couple weeks.)
The impact of SEM is immediate. SEO takes time. Through paid SEM ads, you can start to put your results in front of audiences with just a few clicks. As soon as you launch a campaign, your ads start showing in SERPs. At any time, you can turn ads on to increase visibility or turn them off to stop showing. Conversely, SEO is something that you acquire over time and typically over a long time. It can take months of implementing an SEO strategy before a brand begins to rank on search engines.
QUOTE: “So there’s three things that you really want to do well if you want to be the world’s best search engine you want to crawl the web comprehensively and deeply you want to index those pages and then you want to rank or serve those pages and return the most relevant ones first….. we basically take PageRank as the primary determinant and the more PageRank you have that is the more people who link to you and the more reputable those people are the more likely it is we’re going to discover your page…. we use page rank as well as over 200 other factors in our rankings to try to say okay maybe this document is really authoritative it has a lot of reputation because it has a lot of PageRank … and that’s kind of the secret sauce trying to figure out a way to combine those 200 different ranking signals in order to find the most relevant document.” Matt Cutts, Google
However, if possible, I would like you to expand a bit on your “zombie pages” tip..we run a site where are definitely enough pages to delete (no sessions, no links, probably not even relevant with the main theme of the site, not even important for the architecture of the site)..Nonetheless, I am not very sure what is the best technical decision for these pages…just deleting them from my CMS, redirecting (if there is a relevant alternative) or something else? Unindex them on Search console? what response code they should have? ..