PageRank is a method for ranking web pages based on the link structure of the web. It was developed by Google to help search engines make sense of the vast heterogeneity of the World Web. PageRank works by treating web pages as nodes and links between pages as edges, then recursively propagating importance weights through this link structure. It helps address issues like some pages having more backlinks but from less important places. The PageRank of a page is calculated based on the PageRanks of pages that link to it, normalized by the number of outbound links from those pages.