Cortana starts off by trying to get to know a little bit about you — what you like to do in your spare time, who is important in your life, what sports teams you follow, etc. It uses that information to begin preparing tidbits of information it can show you first thing in the morning, or when it thinks you might need them. It also learns about your habits and becomes more personal over time.

http://www.extremetech.com/extreme/179777-microsofts-cortana-hands-on-the-best-of-google-now-and-siri-combined