This brief review concentrates on three items. First, I report on recent progress in our understanding of the dynamical triggers at work in merger-induced starbursts. Then I address two issues that are often ignored or misunderstood, yet are of fundamental importance to the subject: the large spatial extent of merger-induced starbursts, and the implications of such starbursts for the formation of elliptical galaxies at low and high redshifts.
The basic reason why tidal interactions and mergers help fuel bursts of star formation has been understood for over three decades. Under the headline Stoking the Furnace? Toomre & Toomre (1972) wrote: "Would not the violent mechanical agitation of a close tidal encounter - let alone an actual merger - already tend to bring deep into a galaxy a fairly sudden supply of fresh fuel in the form of interstellar material?" Subsequent numerical simulations that included gas have fully corroborated this notion (e.g., Negroponte & White 1983; Noguchi 1988; Barnes & Hernquist 1991).
Similarly, many observational studies have established beyond any doubt that mergers invigorate star formation well beyond the levels observed in quiescent disk galaxies. As early as 1970, Shakhbazian pointed out the presence of extraordinary stellar "superassociations" with luminosities of up to MV - 15.5 in The Antennae. In a landmark paper, Larson & Tinsley (1978) showed that the UBV colors of Arp's peculiar galaxies can best be explained if tidal interactions engender short, but intense bursts of star formation involving up to ~ 5% of the total mass. Infrared observations confirmed the notion of superstarbursts in major disk-disk mergers (Joseph & Wright 1985). Since then, a steady stream of papers from surveys (e.g., 2dF: Lambas et al. 2003; SDSS: Nikolic et al. 2004) has continued to support and refine this picture. A nice twist was the discovery - fostered by HST's high resolution - that star clusters and, specifically, globular clusters form in large numbers during galactic mergers (Schweizer 1987; Holtzman et al. 1992; Whitmore et al. 1993).