People Count
People Counts are also known as unique visitors - they only count a person once no matter how many times they visit a site in a given month. People Counts are typically used to determine how popular a site is.
Recommendation: To best understand the popularity of a site, you should consider additional metrics beyond People Counts.
For instance, Site X could drive up its People Count by buying a lot of advertising across the Internet. However, many of these people may leave the site immediately. Use Engagement metrics to understand how much time people spend on a site and how many pages they look at on average during each visit to more fully understand the site’s popularity.
this information is from multiple data sources, including ISP, Panel & Toolbar to estimate U.S. traffic.
NEW Google Analytics Code
Google has always strived to give the end user the best and most appropriate results for the end user and has managed this very successfully and will continue to do so.