1.1. Issues/Questions

While progress on distant galaxies has been rapid, there are a number of outstanding questions about the highest redshift objects (those at z > 2) that are the center of a number of debates. Examples of these are (i) what is the effect of dust on the SFR derived from the rest frame UV SED and flux measurements of z > 2 galaxies, (ii) what are the redshifts of the SCUBA submm sources, (iii) what differentiates the optically-detected starbursts from the highly-obscured, submm sources, (iv) what are the masses of the z ~ 2-5 objects, (v) when did the first major star-formation events take place (thus forming the first metals), (vi) what are the physical conditions in high redshift star-forming galaxies, (vii) by what processes, and on what timescales, were the galaxies we see today assembled, and (viii) how do those timescales compare to the timescales for when the bulk of the stars were made?

These questions, and the issues they raise, will be noted during the discussion of the results that are presented in the main body of this paper, and are issues that are encompassed in many discussions of galaxy formation and evolution. As an introduction to developments in high redshift galaxies, and to provide a context for much of the later discussion, a number of items are highlighted first, including (i) timescales, (ii) the recent baryon census, (iii) the photometric ``drop-out'' technique that has been used so successfully to find high redshift galaxies, (iv) the representation of the star formation history of the universe through what has become to be known as the ``Madau'' plot, and (v) the importance of the HST deep imaging fields.

These are followed by more detailed discussions of the results on (i) z ~ 2-5 galaxies, (ii) the SCUBA results, (iii) the latest detections of the very youngest z > 5 galaxies, and (iv) the importance of strongly-lensed sources. Finally, a few comments are made about the future capabilities that will provide the observational framework for the further development of this field, and an assessment of some of the key issues about distant galaxies.