In a video published to the official Google Search Blog Thursday, the Internet giant shed some light on the nuts and bolts of Google Search and the methodology behind its algorithms.
"The Google Search algorithm is made up of several hundred signals that we try to put together to serve the best results for the user," said Rajan Patel, a search scientist at Google. Ranking engineers modify Google's search algorithms on a daily basis, totaling more than 500 improvements over the course of a year.
According to the video released by Google, when an algorithm is modified, the company uses two methods to test the accuracy of new search results, before fully releasing it to its users. The first method relies on professionally trained "raters" who compare the relevancy of one batch of query results to another. The second method of QA testing done by Google Search is with a small batch of real users in a closed environment called the "sandbox".
After testing has taken place and sufficient data is recorded, a search analyst interprets the findings and presents it to a team of engineers. Finally, before the algorithm change is officially confirmed, a "launch decision" meeting consisting of the head of search team decides the fate of the modification.
"While an improvement to the algorithm may start with a creative idea, it always goes through a process of rigorous scientific testing," Google Fellow Amit Singhal wrote in the blog post. "Simply put: if the data from our experiments doesn’t show that we’re helping users, we won’t launch the change."
Most of the changes made to Google's search algorithms are so minor that users don't notice the difference. However, in February Google activated a major update to its search algorithm in an attempt to combat "content farms", which generate low-quality content at high volumes. One such content farm, Demand Media, which profits from publishing articles littered with buzzwords in an attempt to rank higher in Google Search, took a direct hit from the algorithm change. The young company went public in January, but investors lost confidence weeks later, following Google's algorithm tweak, which buried Demand's links below other, presumably higher quality search results.
Google Search has come a long way since its early days. In 2002, users exploited a vulnerability in Google's under-developed search algorithms, which take into account link exchanges when ranking pages. "Google bombing" as it was dubbed, is the process of creating a large number of links to cause a page to rank higher. The idea seems simple, but it was just one evolutionary aspect of search that Google had to learn from.
Check out the video (below) to learn more about Google's process behind tweaking its well-guarded algorithm.