The scientific literature is a place where link persistence is crucial to the public knowledge. A 2013 study in BMC Bioinformatics analyzed 15,000 links in abstracts from Thomson Reuters’ Web of Science citation index, founding that the median lifespan of Web pages was 9.3 years, and just 62% were archived. The median lifespan of a Web page constitutes high-degree variable, but its order of magnitude usually is of some months.
Organic search results are free and display below Google Ads and sometimes local results. Google uses a sophisticated algorithm to determine which sites rank highest for organic search results based on keyword usage, relevance, site design, and other factors. Generally, Google provides the highest quality, most relevant results based on the keyword(s) used by the searcher.