  Extragalactic starbursts induced by gravitational interactions can now be
studied from z = ~0 to ~2. The evidence that mergers of gas-rich galaxies tend
to trigger galaxy-wide starbursts is strong, both statistically and in
individual cases of major disk-disk mergers. Star formation rates appear
enhanced by factors of a few to ~10^3 above normal. Detailed studies of nearby
mergers and ULIRGs suggest that the main trigger for starbursts is the rapidly
mounting pressure of the ISM in extended shock regions, rather than high-
velocity, ~50 - 100 km/s cloud-cloud collisions. Numerical simulations
demonstrate that in colliding galaxies the star formation rate depends not only
on the gas density, but crucially also on energy dissipation in shocks. An
often overlooked characteristic of merger-induced starbursts is that the
spatial distribution of the enhanced star formation extends over large scales
(~10 - 20 kpc). Thus, although most such starbursts do peak near the galactic
centers, young stellar populations pervade merger remnants and explain why (1)
age gradients in descendent galaxies are mild and (2) resultant cluster systems
are far-flung. This review presents an overview of interesting phenomena
observed in galaxy-wide starbursts and emphasizes that such events continue to
accompany the birth of elliptical galaxies to the present epoch.
