<http://schema.org/description>
"Someone told me that if there are 20 people in a room, there's a 50/50 chance that two of them will have the same birthday. How can such a small group have two people with the same birthday in it?"^^<http://www.w3.org/2001/XMLSchema#string>
<http://people.howstuffworks.com/question2611.htm>