Here is a good explanation on what they are at YC http://www.ycombinator.com/atyc/#officehours http://www.ycombinator.com/atyc/#officehours edit: the question

Here is a good explanation on what they are at YC http://www.ycombinator.com/atyc/#officehours http://www.ycombinator.com/atyc/#officehours edit: the question was answered by katm