What is PageRank?

• “PageRank is [only] one of the methods Google uses to determine a page’s relevance or importance.” 
• “Google uses many factors in ranking. Of these, the PageRank algorithm might be the best known. PageRank evaluates two things: how many links there are to a web page from other pages, and the quality of the linking sites. With PageRank, five or six high-quality links from websites such as www.cnn.com and www.nytimes.com would be valued much more highly than twice as many links from less reputable or established sites.” 
• “PageRank has only ever been an approximation of the quality of a web page and has never had anything to do with the measuring of the topical relevance of a web page. Topical relevance is measured with link context and on-page factors such as keyword density, title tag, and everything else.”