Q-point is an acronym for quiescent point. Q-point is the operating point of the transistor (IC,VCE) at which it is biased. The concept of Q-point is used when transistor act as an amplifying device. Q-point is generally taken to be the intersection point of load line with the output characteristics of the transistor. There can be infinite number of intersection points but q-point is selected in such a way that irrespective of input swing transistor remain in active region. All the input AC signals variations happen around Q-point.