  In recent years the census of known satellites in our own Local Group and in
nearby galaxy groups has increased substantially due to sensitive wide-area
surveys. In the Local Group these surveys have more than doubled its known
galaxy content and extended the galaxy luminosity function to very faint total
magnitudes. Deep ground-based imaging and spectroscopic observations as well as
high-resolution imaging with the Hubble Space Telescope have revolutionized our
understanding of the chemical evolution and star formation histories of the
satellites. We often find long-lasting star formation episodes with low star
formation efficiencies. There is evidence for localized, stochastic enrichment,
and recent searches are now beginning to uncover even extremely metal-deficient
stars. In many satellites evidence for two or more distinct stellar
subpopulations is found. Differing fractions of old populations have been
detected in all satellites studied in sufficient detail so far. Kinematic
measurements support a picture in which satellites are dark-matter dominated,
although recent results indicate that the proposed common mass scale for dwarf
spheroidal galaxies may not hold for very low-mass satellites. When considering
satellite ensembles, we find global morphology-distance and gas-content -
distance relations in all groups studied thus far, but individual star
formation histories also strongly depend on a given satellite's intrinsic
properties.
