Book excerpt: Dielectrics is becoming increasingly important due to the rapid developments in electronics, optoelectronics, photonics and nanotechnology. In the past two decades, research on advanced dielectric materials and related applications has undergone an accelerated growth, due in larger part to the discovery of the superior piezoelectric properties in relaxor single crystals, the development of the lead-free piezoelectric/ferroelectric materials and the renaissance of the multiferroics.This book contains 9 feature articles which, together, provide a comprehensive account on the current state of advanced dielectrics and related phenomena. The first two articles present fundamental knowledge related to the characterization of ferroelectric hysteresis, which is the most widely used method to learn the ferroelectricity experimentally. The latest research progress in relaxor ferroelectric is given in the next two articles. The last five articles are dedicated to the multi-functionality of advanced dielectrics, with emphasis on multiferroic magnetoelectric composites, lead-free piezoceramics, pyroelectric/electrocaloric materials, polymer-based dielectrics, and flexible nanodielectrics.