Where did all this information come from?
The short answer is that ZoomInfo found it on the Web. The longer answer is that the information that makes up this Web Summary was built from dozens or even hundreds of public sources found across the Internet, and intelligently assembled into a single, concise professional profile using ZoomInfo’s proprietary search technology.

Who is ZoomInfo?
ZoomInfo is a summarization search engine that finds useful information about people on the Web. This information is gathered from the same publicly available Web sources that are searched by other major search engines like Yahoo and Google, and accessible to any person surfing the Web. ZoomInfo continually scans millions of corporate Web sites, press releases, electronic news services, SEC filings and other public online sources. From these Websites ZoomInfo automatically compiles a person’s Web Summary, which focuses on their professional achievements and background – the stuff they are proud of

http://www.zoominfo.com/PeopleSearch/how.asp