Usage Data: Usage data, as the name implies, is the data recorded by a website to track different metrics pertaining to its usage. Different companies and analytics platforms define usage data based on different parameters. Usage data is widely considered to be the most important factor when search engine robots, like Google's famous spiders, are cataloging and ranking content.
Most commonly, usage data records the number of unique IP addresses (users) visiting a page, repeat visitors to the site, traffic volume, and pages viewed per visitor. Additionally, depending on the analytics client used, click-through rates, and search terms that were used to find each page of content are also tracked.
While usage data can be useful for businesses and marketers looking for clues to what is driving visitors to web pages, usage data plays a pivotal role in how Googlebot catalogs and ultimately assigns value to web content. Consider, it is possible for a site to generate a lot of traffic through back-link farms and keyword spamming, but usage data takes the power away from those tactics by weighing different components in search algorithms against each other. For instance, a website that has high initial traffic volume but a low number of return users probably isn't relevant. Since Google places a huge amount of importance on content that is relevant and useful for web surfers, comprehensive usage data helps ensure that the sites that deserve their traffic are awarded with better SERP placement.