The dynamo effect has been one of the most challenging in modern physics. It has also been one of the most important, since it is believed that the Earth's magnetic field, that of the Sun and astrophysical magnetic fields in general are produced by dynamos resulting from the motion of electrically conducting fluids. Although predicted by theory, the existence, and more specifically, the dynamics of the dynamo have been controversial for many years. Problems have centred around the difficulty of producing a dynamo in the laboratory, and difficulty in solving the equations. Working laboratory dynamos have now been reported. New ideas have emerged to explain the Earth's and Solar dynamos and their 'strange' evolution. Significant progress has been reported in understanding dynamo action in a variety of astrophysical and laboratory fluid flows. The variety and originality of the presentations here make the book an invaluable source for scientists and students interested in the dynamo problem: physicists, astrophysicists, geophysicists, mathematicians and others.