  Over the past several decades, advances in telescope/detector technologies
and deep imaging techniques have pushed surface brightness limits to ever
fainter levels. We can now both detect and measure the diffuse, extended star
light that surrounds galaxies and permeates galaxy clusters, enabling the study
of galaxy halos, tidal streams, diffuse galaxy populations, and the assembly
history of galaxies and galaxy clusters. With successes come new challenges,
however, and pushing even deeper will require careful attention to systematic
sources of error. In this review I highlight recent advances in the study of
diffuse starlight in galaxies, and discuss challenges faced by the next
generation of deep imaging campaigns.
