QUOTE: “Starting April 21 (2015), we will be expanding our use of mobile-friendliness as a ranking signal. This change will affect mobile searches in all languages worldwide and will have a significant impact in our search results. Consequently, users will find it easier to get relevant, high-quality search results that are optimized for their devices”. GOOGLE

QUOTE: “We expect Ads and SC to be visible. However, some Ads, SC, or interstitial pages (i.e., pages displayed before or after the content you are expecting) make it difficult to use the MC. Pages with Ads, SC, or other features that distract from or interrupt the use of the MC should be given a Low rating.” Google Search Quality Evaluator Guidelines 2019
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.
The transparency you provide on your website in text and links about who you are, what you do, and how you’re rated on the web or as a business is one way that Google could use (algorithmically and manually) to ‘rate’ your website. Note that Google has a HUGE army of quality raters and at some point they will be on your site if you get a lot of traffic from Google.
SEM is a broader term than SEO, and is used to encompass different options available to use a search engine’s technology, including paid ads. SEM is often used to describe acts associated with researching, submitting and positioning a website within search engines.  It includes things such as search engine optimization, paid listings and other search-engine related services and functions that will increase exposure and traffic to your Web site. 

A breadcrumb is a row of internal links at the top or bottom of the page that allows visitors to quickly navigate back to a previous section or the root page. Many breadcrumbs have the most general page (usually the root page) as the first, leftmost link and list the more specific sections out to the right. We recommend using breadcrumb structured data markup28 when showing breadcrumbs.
Write a description that would both inform and interest users if they saw your description meta tag as a snippet in a search result. While there's no minimal or maximal length for the text in a description meta tag, we recommend making sure that it's long enough to be fully shown in Search (note that users may see different sized snippets depending on how and where they search), and contains all the relevant information users would need to determine whether the page will be useful and relevant to them.
The biggest advantage any one provider has over another is experience and resource. The knowledge of what doesn’t work and what will hurt your site is often more valuable than knowing what will give you a short-lived boost. Getting to the top of Google is a relatively simple process. One that is constantly in change. Professional SEO is more a collection of skills, methods and techniques. It is more a way of doing things, than a one-size-fits-all magic trick.
You may not want certain pages of your site crawled because they might not be useful to users if found in a search engine's search results. If you do want to prevent search engines from crawling your pages, Google Search Console has a friendly robots.txt generator to help you create this file. Note that if your site uses subdomains and you wish to have certain pages not crawled on a particular subdomain, you'll have to create a separate robots.txt file for that subdomain. For more information on robots.txt, we suggest this Webmaster Help Center guide on using robots.txt files13.
QUOTE: “The easiest thing is think about what people are gonna type to want to find your site so we had somebody come to a conference and say I want to show up for (Keyword) and we said well have you put the (Keyword) on your page anywhere at all and he hadn’t and sometimes just very simple stuff like that really helps think about what users are gonna type to find your page and then just make sure those keywords are on the page.” Matt Cutts, Google 2013

How do you figure out what keywords your competitors are ranking for, you ask? Aside from manually searching for keywords in an incognito browser and seeing what positions your competitors are in, SEMrush allows you to run a number of free reports that show you the top keywords for the domain you enter. This is a quick way to get a sense of the types of terms your competitors are ranking for.
QUOTE: “News and current events: news about important topics such as international events, business, politics, science, technology, etc. Keep in mind that not all news articles are necessarily considered YMYL (e.g., sports, entertainment, and everyday lifestyle topics are generally not YMYL). Please use your judgment and knowledge of your locale. ● Civics, government, and law: information important to maintaining an informed citizenry, such as information about voting, government agencies, public institutions, social services, and legal issues (e.g., divorce, child custody, adoption, creating a will, etc.). ● Finance: financial advice or information regarding investments, taxes, retirement planning, loans, banking, or insurance, particularly webpages that allow people to make purchases or transfer money online. ● Shopping: information about or services related to research or purchase of goods/services, particularly webpages that allow people to make purchases online. ● Health and safety: advice or information about medical issues, drugs, hospitals, emergency preparedness, how dangerous an activity is, etc. ● Groups of people: information about or claims related to groups of people, including but not limited to those grouped on the basis of race or ethnic origin, religion, disability, age, nationality, veteran status, sexual orientation, gender or gender identity. ● Other: there are many other topics related to big decisions or important aspects of people’s lives which thus may be considered YMYL, such as fitness and nutrition, housing information, choosing a college, finding a job, etc.” Google Search Quality Evaluator Guidelines 2019
Does this article have an excessive amount of ads that distract from or interfere with the main content? (OPTIMISE FOR SATISFACTION FIRST – CONVERSION SECOND – do not let the conversion get in the way of satisfying the INTENT of the page. For example – if you rank with INFORMATIONAL CONTENT with a purpose to SERVE those visitors – the visitor should land on your destination page and not be deviated from the PURPOSE of the page – and that was informational, in this example – to educate. SO – educate first – beg for social shares on those articles – and leave the conversion on Merit and slightly more subtle influences rather than massive banners or whatever that annoy users). We KNOW ads (OR DISTRACTING CALL TO ACTIONS) convert well at the top of articles – but Google says it is sometimes a bad user experience. You run the risk of Google screwing with your rankings as you optimise for conversion so be careful and keep everything simple and obvious.

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.
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
Google WILL classify your site when it crawls and indexes your site – and this classification can have a DRASTIC effect on your rankings. It’s important for Google to work out WHAT YOUR ULTIMATE INTENT IS – do you want to be classified as a thin affiliate site made ‘just for Google’, a domain holding page or a small business website with a real purpose? Ensure you don’t confuse Google in any way by being explicit with all the signals you can – to show on your website you are a real business, and your INTENT is genuine – and even more important today – FOCUSED ON SATISFYING A VISITOR.
QUOTE: “You heard right there is no duplicate content penalty… I would avoid talking about duplicate content penalties for spam purposes because then it’s not about duplicate content then it’s about generating in a very often in an automated way content that is not so much duplicated as kind of fast and scraped from multiple places and then potentially probably monetized in some way or another and it just doesn’t serve any purpose other than to gain traffic redirect traffic maybe make some money for the person who created it this is not about content that gets really sort of created for any kind of reason other than just to be there so I person I don’t think about it as duplicate content there is just this disparity it’s the same thing as saying that maybe we created gibberish is some sort of a duplicate content of words but otherwise also exists like I I would really separate those two issues because the things that Aamon led in with URLs generated on WordPress and the things they were going to discuss today later maybe about e-commerce sites and so on I wouldn’t want people to confuse those two.”  Andrey Lipattsev, Google 2016
Robots.txt is not an appropriate or effective way of blocking sensitive or confidential material. It only instructs well-behaved crawlers that the pages are not for them, but it does not prevent your server from delivering those pages to a browser that requests them. One reason is that search engines could still reference the URLs you block (showing just the URL, no title or snippet) if there happen to be links to those URLs somewhere on the Internet (like referrer logs). Also, non-compliant or rogue search engines that don't acknowledge the Robots Exclusion Standard could disobey the instructions of your robots.txt. Finally, a curious user could examine the directories or subdirectories in your robots.txt file and guess the URL of the content that you don't want seen.