  The epoch of galaxy assembly from 2<=z<=4 marks a critical stage during the
evolution of today's galaxy population. During this period the star-formation
activity in the Universe was at its peak level, and the structural patterns
observed among galaxies in the local Universe were not yet in place. A variety
of novel techniques have been employed over the past decade to assemble
multiwavelength observations of galaxies during this important epoch. In this
primarily observational review, I present a census of the methods used to find
distant galaxies and the empirical constraints on their multiwavelength
luminosities and colors. I then discuss what is known about the stellar content
and past histories of star formation in high-redshift galaxies; their
interstellar contents including dust, gas, and heavy elements; and their
structural and dynamical properties. I conclude by considering some of the most
pressing and open questions regarding the physics of high-redshift galaxies,
which are to be addressed with future facilities.
