Galactic winds are ubiquitous in most rapidly star-forming galaxies in both the local and high-redshift universe. They shape the galaxy luminosity function, flattening its faint-end slope compared to the halo mass function, and affect the chemical evolution of galaxies, determining the mass-metallicity relation, regulating star formation over cosmic time, and polluting the intergalactic medium (IGM) with metals. Although important, the physics of galactic winds is still unclear. Many theoretical mechanisms have been proposed. Winds may be driven by the heating of the interstellar medium by overlapping supernovae, cosmic rays, the radiation pressure by continuum absorption and scattering of starlight on dust grains, or the momentum input from SNe. However, the comparison between theory and observation is incomplete. The growing observations of emission and absorption of cold molecular, cool atomic, and ionized gas in galactic outflows in a large number of galaxies have not been well explained by any models over a vast range of galaxy parameters. A full understanding of these issues requires both better theoretical explorations and comparisons with new and existing observations. In this presentation, I will be taking about the theoretical models of both radiation pressure- and supernova-driven galactic winds, and compared these models with observations.