  We summarize recent advances in the determination of the cosmic history of
star formation and other properties of high-z galaxies, and the relevance of
this information in our understanding of the formation of structures. We
emphasize the importance of dust reprocessing in the high--z universe, as
demonstrated in particular by IR and sub-mm data. This demand a panchromatic
approach to observations and suitable modelling tools. We spend also some words
on expectations from future instruments.
