What is Superconducting Quantum Interference Device (SQUID)

This chapter is composed by three parts. The first is an introductory part, providing general information about magnetism and related phenomena. Magnetic materials are also discussed and presented. Afterwards, the magnetic field and various measurement techniques are discussed. In the second part, different magnetic sensors used in a laboratory or space are presented. Magnetic sensors that are discussed include anisotropic magneto-resistance (AMR), giant magneto-resistance (GMR), giant magneto-impedance (GMI), flux-gate, and superconducting quantum interference device (SQUID). Although some of them may be outdated and well known, they are widespread, and they still pose an excellent choice for certain applications. Advances in magnetometers also presented in order to provide the reader with the recent trends in the field. Magnetic cleanliness is an important factor both in calibration and in normal operation of a system; in the third part, current techniques to isolate a system from the external magnetic field providing cleanliness are discussed.