Gravitational lensing is now sufficiently well understood to be used as an investigative tool in a variety of astrophysical applications: determination of the Hubble constant; probing the dark matter context of galaxies; mapping of the universe; identification of otherwise invisible large-scale structures. Each chapter of Gravitational Lensing offers self-contained coverage of a single subfield, with the double aim of describing simply the basics of the theory, and of reviewing the most recent developments and applications foreseen in the near future. The book will thus be particularly useful as a high-level textbook for nonspecialist researchers and advanced students wishing to become familiar with the field all the way up to the forefront of research.