Humanoid robots include a mobile base (walking or rolling) and manipulation devices, usually two arms. By the number of actuators and accessible workspace, they are certainly the most complex robotics systems designed. Unlike classical robots in industry, they have to interact directly with humans, and unlike service robots which have usually only a mobility capacity or limited manipulation, this interaction is a very close one. It is therefore mandatory that the safety and human-friendly aspects of this interaction be addressed as such, considering the problem in its entirety. This paper discusses these issues considering several constraints that must be respected by the robot motion planning system, related to the human-robot interaction distance. It introduces the concepts of safety distance, social distance, manipulation zone, and friendly posture.