Abstract
A general physical picture of superconductor weak‐link junctions is outlined with emphasis on phenomena relevant to device applications. The total junction current contains a dissipative quasiparticle component nearly analogous to the current in a normal‐state junction plus an electron‐pair component responsible for superconducting effects such as the Josephson effects. Stochastic relaxation processes such as have been commonly associated with vortex motion and flux flow sometimes perturb the pair current and must also be taken into account.