The Hubble Deep Field is a rather uninteresting region 2.7 x 2.7 arcmin in size at high galactic latitude (low galactic extinction, no known interesting sources) that was observed for a total of 150 orbits by the Hubble Space Telescope Wide Field Planetary Camera. Images were taken in four filters centered roughly at 3000, 4000, 6000 and 8000 Angstroms.
The field is full of galaxies, most of which are at high redshifts. Here are a few conclusions derived from the observations of such distant galaxies.
A large fraction of distant galaxies have disturbed morphologies.
The star formation rate was much higher in the disks of these galaxies than in nearby spiral disks.
Some elliptical galaxies were fully formed and quite "old" at z > 1 (look-back time > 8 Gyr).
There is a large population of luminous blue galaxies at z > 1. Their local counterparts are not yet identified.
The Hubble Deep Field image direct from STScI.
A cool interactive site on the HDF at the U of Hawaii
A consequence of Hubble Deep Field: An extremely distant galaxy.