Arrays of Josephson junctions are powerful superconducting devices with both technological and basic applications. In this review article, we describe how these devices work as well as their transport and magnetic properties. We also show how they can be used to explain some of the controversial properties of granular superconducting systems, like Paramagnetic Meissner Effect (PME), Vortex Avalanche (VA) and other granularity-related e ects.
