  Based on an Invited Plenary Talk given at ``Workshop on Physics and
Experiments with Linear $e^+e^-$ Colliders,'' Waikoloa, Hawaii, April 26--30,
1993. This paper reviews theoretical issues concerning the structure of vector
bosons, with emphasis on deviations of triple-vector-boson interactions from
the predictions of the Standard Model. Particular emphasis is on the role of
gauge invariance in understanding the behavior of vector particles over energy
scales large compared to their masses.
