Observed Properties of High-redshift Galaxies

This chapter summarizes the observational results obtained up to now for galaxies with redshifts z > 2. Historically, the first galaxies to be detected at such redshifts were (rest-frame) UV-bright starburst galaxies∈dex{starburst galaxies}. Therefore, starburst galaxies have been investigated much more thoroughly than other types of high-redshift objects. Only recently the interest has shifted toward the passively evolving high-redshift galaxies, which became accessible due to new space-based infrared instrumentation. These high-redshifts systems are of particular astrophysical interest since (as pointed out in Sect. \ref{galaxies}) in the local universe the passively evolving ellipticals and the spheroidal bulges of the disk galaxies contain most of the cosmic stellar mass. Therefore, the history and origin of these systems are among the key questions of astrophysics.