Abstract: Line-intensity mapping (LIM) experiments use the integrated intensity at a given frequency, targeting well-known spectral lines to infer the redshift of the signal and build three-dimensional maps of cosmic volumes. This provides a noisy map from all the galaxies, and grants access to redshifts beyond the reach of galaxy surveys, and glean otherwise inaccessible astrophysical information. I will review the potential of these observations and discuss potential applications for cosmology, such as extending the cosmic distance ladder to significantly higher redshifts using BAO, and the sensitivity to exotic radiative decays of dark matter or neutrinos.