  How did galaxies form and evolve? This is one of the most challenging
questions in astronomy today. Answering it requires a careful combination of
observational and theoretical work to reliably determine the observed
properties of cosmic bodies over large portions of the distant Universe on the
one hand, and accurately model the physical processes driving their evolution
on the other. Most importantly, it requires bringing together disparate
multi-wavelength and multi-resolution spectro-photometric datasets in an
homogeneous and well-characterized manner so that they are suitable for a
rigorous statistical analysis. The Herschel Extragalactic Legacy Project (HELP)
funded by the EC FP7 SPACE program aims to achieve this goal by combining the
expertise of optical, infrared and radio astronomers to provide a
multi-wavelength database for the distant Universe as an accessible value-added
resource for the astronomical community. It will do so by bringing together
multi-wavelength datasets covering the 1000 deg$^2$ mapped by Herschel
extragalactic surveys in an homogeneous and well-characterized manner, creating
a joint lasting legacy from several ambitious sky surveys.
