The site loads a Java web application that lets you type in any name. As you start typing, it will start showing you a graph of the popularity of each name and how popular it was in each decade for over the past 100 years. The taller the graph is during a particular period of time means the name was more popular. You can easily see trends for your favorite name over the years.

As we can see, the name "John" has declined in popularity over the years. One caveat is to keep an eye on the scale. It always rescales to fit the space. While "John" has declined in popularity, it "fell" from #1 Ranked in the 1880s to #18th in 2004.