The PageRank algorithm was developed by Larry Page and Sergey Brin in 1996 to rank the importance of web pages. It measures a page's importance based on the number and quality of links to it, viewing the web as a directed graph. The algorithm models a random web surfer and calculates the probability of ending up on each page. It has since been refined by Google but remains an important factor in search engine results. Variations of PageRank can also be applied to other networks like ranking NFL teams based on game outcomes.