Questions and answers

It is an algorithm for ranking pages based on links, proposed by Larry Page and Sergey Brin at Stanford and described in the paper "The Anatomy of a Large-Scale Hypertextual Web Search Engine" (1998). The idea is that a link to a page is like a "vote", and a vote from a page that many others link to carries more weight.

From the early 2000s, the Google Toolbar displayed a page's PageRank on a scale from 0 to 10. It was a simplified public display, updated only occasionally, not a full picture of how the search engine evaluated the page.

Nowhere. Public updates to the score stopped at the end of 2013, and in 2016 Google removed it from public view for good. If a service shows a number called PageRank, it is that service's own estimate.

They do, just not as a single visible number. Inside search, links are still taken into account among many other signals. Search engines don't disclose the details, so any precise "link weight formulas" you find online are guesswork.

Common reasons: the page can't be opened without logging in or returns an error, its section is blocked in robots.txt, it carries a noindex directive, nothing links to it, or the search engine simply hasn't crawled it yet. Google Search Console and Yandex Webmaster help you check.

Not reliably. robots.txt is the Robots Exclusion Protocol, which appeared in 1994 and was standardised as RFC 9309 in 2022. It controls crawling, but a page can still end up in the index, for example if other sites link to it.

No, but it helps. The Sitemaps protocol (sitemaps.org) has existed since 2006 and is supported by the major search engines. A sitemap indicates which addresses you want to show, but it does not oblige a search engine to index them.

Search engines don't promise exact timelines, and we won't name any either. Links to the page from pages the search engine already knows, a sitemap and webmaster tools all help it discover the page sooner.

These are link attributes that tell a search engine what kind of link it is. The rel="nofollow" attribute appeared in 2005; in 2019 Google added rel="sponsored" for paid links and rel="ugc" for user-generated content, and began treating nofollow as a hint rather than a strict directive.

Search engine policies prohibit it. The link spam section of Google's spam policies describes buying and selling links to manipulate rankings as a violation. Paid links must be marked sponsored or nofollow.

In 2018 Yandex replaced its thematic citation index (TIC) with the site quality index (SQI, or IKS in Russian). We don't attempt to explain how SQI is calculated; see Yandex Help for webmasters.

No. DR, DA and similar domain "authority" metrics are estimates from individual third-party services, not search engine data. They can be used for rough comparisons, but they shouldn't be mistaken for how Google or Yandex evaluates a site.