Google has a LONG list of technical requirements it advises you meet, on top of all the things it tells you NOT to do to optimise your website. Meeting Google’s technical guidelines is no magic bullet to success – but failing to meet them can impact your rankings in the long run – and the odd technical issue can actually severely impact your entire site if rolled out across multiple pages.
However, we do expect websites of large companies and organizations to put a great deal of effort into creating a good user experience on their website, including having helpful SC. For large websites, SC may be one of the primary ways that users explore the website and find MC, and a lack of helpful SC on large websites with a lot of content may be a reason for a Low rating.
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.
QUOTE: “Cleaning up these kinds of link issue can take considerable time to be reflected by our algorithms (we don’t have a specific time in mind, but the mentioned 6-12 months is probably on the safe side). In general, you won’t see a jump up in rankings afterwards because our algorithms attempt to ignore the links already, but it makes it easier for us to trust the site later on.” John Mueller, Google, 2018
Having a different description meta tag for each page helps both users and Google, especially in searches where users may bring up multiple pages on your domain (for example, searches using the site: operator). If your site has thousands or even millions of pages, hand-crafting description meta tags probably isn't feasible. In this case, you could automatically generate description meta tags based on each page's content.
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.
SEO is also about making your search engine result relevant to the user's search query so more people click the result when it is shown in search. In this process, snippets of text and meta data are optimized to ensure your snippet of information is appealing in the context of the search query to obtain a high CTR (click through rate) from search results.