<p>Bernhard Gleich introduces Magnetic Particle Imaging (MPI) including all aspects that are necessary for a complete understanding. MPI is a new imaging modality invented by Bernhard Gleich and Jürgen Weizenecker. The method is capable of imaging the distribution of superparamagnetic iron oxide particles (SPIOs) with high sensitivity, high spatial resolution, and high imaging speed. The author summarizes the results of a number of original papers and countless innovations he has elaborated in the young discipline of magnetic particle imaging.</p>