Emission Line Galaxies in Clusters

At the present epoch, clusters of galaxies are known to be a hostile environment for emission-line galaxies, which are more commonly found in low density regions outside of clusters. In contrast, going to higher redshifts the population of emission-line galaxies in clusters becomes progressively more conspicuous, and large numbers of star-forming late-type galaxies are observed. I present an overview of the observational findings and the theoretical expectations regarding the evolution of emission-line galaxies in dense environments, discussing the properties of these galaxies and the current evidence for environmental influences on their evolution.