Google announced Chrome OS on July 7, 2009,[15] describing it as an operating system in which both applications and user data reside in the cloud. The concept was new enough to confuse users and analysts, as well as Google co-founder Sergey Brin, who, at first, didn't realize his data did not reside on his personal computer, but could be accessed from any machine running the operating system.[16] To ascertain marketing requirements, the company relied on informal metrics, including monitoring the usage patterns of some 200 Chrome OS machines used by Google employees. Developers also noted their own usage patterns. Matthew Papakipos, former[17] engineering director for the Chrome OS project, put three machines in his house and found himself logging in for brief sessions: to make a single search query or send a short email