As the Web grows and Internet user behaviors change, Google’s understanding of what is important must also change as well. The search engine updates its algorithm almost daily and works to return the most relevant results to its users for a given query. Additionally, because of spammy content infiltrating search results, what returns as a relevant result today may not do so tomorrow.
While certain algorithm updates receive more fanfare than others (e.g., the recent “Farmer / Panda” Update), Google is said to manipulate its search results more than ten times per week. These updates reflect what users expect to see in search results, and also how information circulates the Web.