PageRank (PR) is Google’s main method of ranking web pages for placement on a search engine results page (SERP). PageRank refers to the system and the algorithmic method that Google uses to rank pages as well as the numerical value assigned to pages as a score.
Normally Googlebot, Google’s webcrawler, follows links on web pages to index sites and tally links as votes for a given site’s importance. The number of links to a page and the authority of the pages where the links appear both affect how much they impact the linked site’s ranking.
Google Toolbar, a user-installed add-on for quick searches, is one of the first spots most people have encountered PageRank. The add-on is now only available for Internet Explorer (IE) since its features were rolled into the Chrome browser.
Google Toolbar displays the PageRank for the current page along with a score out of ten and a bar graph. This quick PageRank reference method became heavily used by search engine optimization (SEO) specialists to evaluate both their own sites and others. PageRank visibility resulted in many unsolicited link request emails and a great deal of link spam. Google has since decided to drop PageRank from its toolbar and the ranking will again become a background metric that is not easily viewable by users.
Other metrics that Google and other search engines use to determine the importance of a website include:
- The page’s speed.
- The page’s longevity on the web.
- The time users spend on the site.
- The inclusion of anchor text providing a clear indication of where links go.
- The use of exploitative SEO tactics.
The nofollow tag stops links from being tallied for PageRank. Webmasters can use nofollow to avoid negative SEO from spam that ends up on a page with open comments, for example. Preventing crawlers from following links means that they are not considered in determining PageRank and placement in SERP.
Although the name is self-explanatory – PageRank is used to rank pages – it is also said to be named after Larry Page, who founded Google and developed PageRank along with Sergey Brin.