The iCub is a humanoid robot shaped as a child of about four years of age available as an open system platform (following GPL license) that was originally designed by a consortium of 11 partners within the RobotCub Integrated Project funded by European Commission with the purpose of supporting research in artificial embodied cognition. The iCub is endowed with 53 degrees of freedom; it can crawl on all fours and sit up; its hands allow dexterous manipulation and its head and eyes are fully articulated. It has visual, vestibular, auditory, and haptic sensory functionalities. The talk will start from an initial overview of the iCub bodyware capabilities and software architecture that represent fundamental tools in the study of how a cognitive behavior can emerge as a learning process from the interaction with external environment. Afterwards, the presentation will focus on the collaboration among the large community of scientists that has dramatically grown in number over the past two-three years sharing iCub as an effective research platform where to put to the test theories, compare results and accumulate an open repository of experimental facilities: therefore, several examples of these activities will be analyzed in details.