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My interest in galactic winds was stimulated during the time I spent at Steward Observatory as a Bart Bok Fellow during the early 1980's. At that time, Ray Weymann was working on a theoretical model for cosmic-ray-driven thermal winds in QSOs (see Weymann et al. 1982), and I recall discussing with Ray about how one might go about detecting the hydrodynamical consequences of such flows on the surrounding interstellar and intergalactic media.

These musings did not bear fruit until several years later (McCarthy, van Breugel, & Heckman 1987; Heckman, Armus, & Miley 1987, 1990) when my colleagues and I drew attention to evidence for global outflows from the class of powerful, dusty starbursts that had been discovered by IRAS. By now, it is well-established that galactic-scale outflows of gas ("superwinds") are commonplace in the most actively star-forming galaxies in both the local universe (e.g. Lehnert & Heckman 1996; Dahlem, Weaver, & Heckman 1998; Veilleux et al. 1998) and at high redshift (e.g. Pettini et al. 2001).

In this contribution, I will review the dynamical evolution of superwinds (section 2), the nature and origin of their emission and absorption (section 3), their demographics (section 4), their estimated outflow rates (section 5), and their likely fate (section 5). Finally, I will describe their potential implications for the evolution of galaxies and the inter-galactic medium (section 6).