PageRank is a proprietary mathematical algorithm developed and owned by Google to evaluate the importance and relevance of web pages. It’s name originated from one of Google’s founders, Larry Page.
PageRank operates on a link analysis algorithm, centering around the idea that not all links are created equal. The primary function of PageRank is to assign numerical weighting to each element of a set of hyperlinked documents, like the World Wide Web (WWW), which aids in measuring the importance or relevance of a webpage.
For example, suppose web page A hyperlinks to web page B, PageRank interprets this link as a vote of trust or confidence by page A for page B. However, PageRank also evaluates the quantity and quality of links to a certain page to get an estimation of a webpage’s significance. It supposes that more important websites are likely to get more links from other web pages.
The original version of PageRank works by counting the number and quality of links to a page to determine an estimate of how important the page is. The underlying assumption is that more important websites are likely to receive more links from other websites.
According to “Introduction to Information Retrieval,” a book by Christopher Manning, Prabhakar Raghavan, and Hinrich Schütze, PageRank or PR(A) can be calculated using a formula:
PR(A) = (1-d) + d(PR(t1)/C(t1) + … + PR(tn)/C(tn))
Where:
PR(A) is the PageRank of page A,
PR(t1) is the PageRank of pages ti which link to page A,
C(t1) is the number of outbound links on page ti and
d is a damping factor which can be set between 0 and 1.
The damping factor in the PageRank computation is a scalar that Google includes in every calculation. It’s often set to 0.85, which means that the PageRank of an entire site can be interpreted as constantly leaking away 15% of its value.
An example of the impact and importance of PageRank can be seen in SEO (Search Engine Optimization) practices, where experts will focus on backlinking strategies to increase the PageRank of a specific site or page, understanding that a higher PageRank often translates to a higher position in Google’s search engine results, according to Moz, a recognized source for SEO knowledge.
Google has officially stopped updating the PageRank that it displays to the public in 2016. However, this doesn’t mean that the underlying principles of PageRank are no longer utilized by Google. PageRank is likely continuing to play a role in the algorithm Google uses to rank search results, but it’s just one of thousands of signals, according to Search Engine Journal.
Sources:
1. “Introduction to Information Retrieval” by Christopher Manning, Prabhakar Raghavan, and Hinrich Schütze.
2. Moz.com
3. Search Engine Journal.
