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.
Wikipedia, naturally, has an entry about PageRank with more resources you might be interested in. It also covers how some sites using redirection can fake a higher PageRank score than they really have. And since we’re getting all technical — PageRank really isn’t an actual 0 to 10 scale, not behind the scenes. Internal scores are greatly simplified to match up to that system used for visible reporting.
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. 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 in addition to their URL submission console. Yahoo! formerly operated a paid submission service that guaranteed crawling for a cost per click; however, this practice was discontinued in 2009.
Paid per click marketing is not about blindly paying Google to drive clicks to your site. It is about knowing how much to pay for each click and understanding which type of consumer you ought to be paying to attract. It is also about listening to signals provided by clicks that result in both bounces AND your desired conversion goals to make the necessary changes to your keyword lists, ads and landing pages.