Search engines may penalize sites they discover using black or grey hat methods, either by reducing their rankings or eliminating their listings from their databases altogether. Such penalties can be applied either automatically by the search engines' algorithms, or by a manual site review. One example was the February 2006 Google removal of both BMW Germany and Ricoh Germany for use of deceptive practices.[54] Both companies, however, quickly apologized, fixed the offending pages, and were restored to Google's search engine results page.[55]
If you take money online, in any way, you NEED to have an accessible and satisfying ‘customer service’ type page. Google says, “Contact information and customer service information are extremely important for websites that handle money, such as stores, banks, credit card companies, etc. Users need a way to ask questions or get help when a problem occurs. For shopping websites, we’ll ask you to do some special checks. Look for contact information—including the store’s policies on payment, exchanges, and returns. “ Google urges quality raters to be a ‘detective’ in finding this information about you – so it must be important to them.
That content CAN be on links to your own content on other pages, but if you are really helping a user understand a topic – you should be LINKING OUT to other helpful resources e.g. other websites.A website that does not link out to ANY other website could be interpreted accurately to be at least, self-serving. I can’t think of a website that is the true end-point of the web.

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.

A poor 404 page and user interaction with it, can only lead to a ‘poor user experience’ signal at Google’s end, for a number of reasons. I will highlight a poor 404 page in my audits and actually programmatically look for signs of this issue when I scan a site. I don’t know if Google looks at your site that way to rate it e.g. algorithmically determines if you have a good 404 page – or if it is a UX factor, something to be taken into consideration further down the line – or purely to get you thinking about 404 pages (in general) to help prevent Google wasting resources indexing crud pages and presenting poor results to searchers. I think rather that any rating would be a second order scoring including data from user activity on the SERPs – stuff we as SEO can’t see.

Being ‘relevant’ comes down to keywords & key phrases – in domain names, URLs, Title Elements, the number of times they are repeated in text on the page, text in image alt tags, rich markup and importantly in keyword links to the page in question. If you are relying on manipulating hidden elements on a page to do well in Google, you’ll probably trigger spam filters. If it is ‘hidden’ in on-page elements – beware relying on it too much to improve your rankings.
At the moment, I don’t know you, your business, your website, your resources, your competition or your product. Even with all that knowledge, calculating ROI is extremely difficult because ultimately Google decides on who ranks where in its results – sometimes that’s ranking better sites, and sometimes (often) it is ranking sites breaking the rules above yours.

I think it makes sense to have unique content as much as possible on these pages but it’s not not going to like sync the whole website if you don’t do that we don’t penalize a website for having this kind of deep duplicate content and kind of going back to the first thing though with regards to doorway pages that is something I definitely look into to make sure that you’re not running into that so in particular if this is like all going to the same clinic and you’re creating all of these different landing pages that are essentially just funneling everyone to the same clinic then that could be seen as a doorway page or a set of doorway pages on our side and it could happen that the web spam team looks at that and says this is this is not okay you’re just trying to rank for all of these different variations of the keywords and the pages themselves are essentially all the same and they might go there and say we need to take a manual action and remove all these pages from search so that’s kind of one thing to watch out for in the sense that if they are all going to the same clinic then probably it makes sense to create some kind of a summary page instead whereas if these are going to two different businesses then of course that’s kind of a different situation it’s not it’s not a doorway page situation.”
QUOTE: “In place of a pop-up try a full-screen inline ad. It offers the same amount of screen real estate as pop-ups without covering up any content. Fixing the problem depends on the issue you have for example if it’s a pop-up you’ll need to remove all the pop-up ads from your site but if the issue is high ad density on a page you’ll need to reduce the number of ads” Google, 2017
Many search engine marketers think who you link out to (and who links to you) helps determine a topical community of sites in any field or a hub of authority. Quite simply, you want to be in that hub, at the centre if possible (however unlikely), but at least in it. I like to think of this one as a good thing to remember in the future as search engines get even better at determining topical relevancy of pages, but I have never actually seen any granular ranking benefit (for the page in question) from linking out.
Don’t break Google’s trust – if your friend betrays you, depending on what they’ve done, they’ve lost trust. Sometimes that trust has been lost altogether. If you do something Google doesn’t like such as manipulate it in a way it doesn’t want, you will lose trust, and in some cases, lose all trust (in some areas). For instance, your pages might be able to rank, but your links might not be trusted enough to vouch for another site. DON’T FALL OUT WITH GOOGLE OVER SOMETHING STUPID
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.[40] 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[41] in addition to their URL submission console.[42] Yahoo! formerly operated a paid submission service that guaranteed crawling for a cost per click;[43] however, this practice was discontinued in 2009.
Note that Google is pretty good these days at removing any special characters you have in your page title – and I would be wary of trying to make your title or Meta Description STAND OUT using special characters. That is not what Google wants, evidently, and they do give you a further chance to make your search snippet stand out with RICH SNIPPETS and SCHEMA mark-up.
Sometimes, Google turns up the dial on demands on ‘quality’, and if your site falls short, a website traffic crunch is assured. Some sites invite problems ignoring Google’s ‘rules’ and some sites inadvertently introduce technical problems to their site after the date of a major algorithm update and are then impacted negatively by later refreshes of the algorithm.
Good news for web designers, content managers and search engine optimisers! ” Google clearly states, “If the website feels inadequately updated and inadequately maintained for its purpose, the Low rating is probably warranted.” although does stipulate again its horses for courses…..if everybody else is crap, then you’ll still fly – not much of those SERPs about these days.
NOTE, in 2019, the HTML title element you choose for your page, may not be what Google chooses to include in your SERP snippet. The search snippet title and description is very much QUERY & DEVICE dependant these days. Google often chooses what it thinks is the most relevant title for your search snippet, and it can use information from your page, or in links to that page, to create a very different SERP snippet title.
That content CAN be on links to your own content on other pages, but if you are really helping a user understand a topic – you should be LINKING OUT to other helpful resources e.g. other websites.A website that does not link out to ANY other website could be interpreted accurately to be at least, self-serving. I can’t think of a website that is the true end-point of the web.
If you have original, quality content on a site, you also have a chance of generating inbound quality links (IBL). If your content is found on other websites, you will find it hard to get links, and it probably will not rank very well as Google favours diversity in its results. If you have original content of sufficient quality on your site, you can then let authority websites – those with online business authority – know about it, and they might link to you – this is called a quality backlink.
For me, when SEO is more important than branding, the company name goes at the end of the tag, and I use a variety of dividers to separate as no one way performs best. If you have a recognisable brand – then there is an argument for putting this at the front of titles – although Google often will change your title dynamically – sometimes putting your brand at the front of your snippet link title itself. I often leave out branding. There is no one size fits all approach as the strategy will depend on the type of page you are working with.
“Doorways are sites or pages created to rank highly for specific search queries. They are bad for users because they can lead to multiple similar pages in user search results, where each result ends up taking the user to essentially the same destination. They can also lead users to intermediate pages that are not as useful as the final destination.
QUOTE: “I think that’s always an option. Yeah. That’s something that–I’ve seen sites do that across the board,not specifically for blogs, but for content in general, where they would regularly go through all of their content and see, well, this content doesn’t get any clicks, or everyone who goes there kind of runs off screaming.” John Mueller, Google 
Onsite, consider linking to your other pages by linking to pages within main content text. I usually only do this when it is relevant – often, I’ll link to relevant pages when the keyword is in the title elements of both pages. I don’t go in for auto-generating links at all. Google has penalised sites for using particular auto link plugins, for instance, so I avoid them.

When would this be useful? If your site has a blog with public commenting turned on, links within those comments could pass your reputation to pages that you may not be comfortable vouching for. Blog comment areas on pages are highly susceptible to comment spam. Nofollowing these user-added links ensures that you're not giving your page's hard-earned reputation to a spammy site.

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.