Few bird species have such a close and diverse relationship with humans as the blue tit. It regularly visits gardens and settlements, breeds in nest boxes hung here, and visits our feeding stations in winter. On the other hand, it serves as an important model organism for numerous scientific studies. This volume presents various aspects of the life of this charming songbird. In addition to fundamental data on the biology and ecology of the species across its entire range, the results of our own studies on alpine blue tit populations are presented in detail. Questions regarding breeding biology, such as nest building, egg physiology, and rearing of young, are discussed, as well as various aspects of habitat choice and winter space use. Additionally, results from new physiological and molecular biological studies are addressed.