I review the recent instrumental progresses which allow to directly observe galaxy properties at the earliest epochs of the Universe. This leads to the derivation of fundamental quantities, such as the epoch of massive galaxy formation or the universal history of heavy element formation. Star formation history shows a gradual decline since the last 8-9 Gyr. The bulk of present-day stellar mass and metal content was formed at redshifts 0.5 to ~3, which is consistent with hierarchical scenarii of galaxy formation. The numerous uncertainties related to these determinations are emphasized, including those linked to stellar physics.