For a century, galaxy studies have been based on two-dimensional images and spectra of their energy distribution obtained at a limited number of spatial locations on the galaxies. In the past decade, this kind of observations has been replaced by a new wave of instruments, which are able to obtain spectra at every location over the galaxies, producing a full three-dimensional view. I will give an overview of the new discoveries in our understanding of galaxy formation, produced by this observational revolution.