I review the observational characteristics of intermediate-to-high redshift star forming galaxies , including their star formation rates , dust extinctions , ISM kinematics , and chemical compositions .
I present evidence that the mean rate of metal enrichment , \Delta { Z } / \Delta { z } , from z = 0—3 , as determined from nebular oxygen abundance measurements in star forming galaxies , is 0.15 dex per redshift unit for galaxies more luminous than M _ { B } = -20.5 .
This rate of chemical enrichment is consistent with the chemical rise in Galactic disk stars .
It is less dramatic than , but perhaps consistent with , the enrichment rate of 0.18–0.26 \pm 0.07 dex per redshift unit seen in Damped Ly \alpha systems , and it is much less than predicted by many cosmological evolution models .
The high-redshift galaxies observed to date are the most luminous examples from those epochs , and thus , trace only the greatest cosmological overdensities .
Star formation in the first 1-2 Gyr appears sufficient to elevate ambient metallicities to near or above the solar value , implying efficient production and retention of metals in these densest environments .