  We review results on the dynamics of warped gaseous discs. We consider tidal
perturbation of a Keplerian disc by a companion star orbiting in a plane
inclined to the disc. The perturbation induces the precession of the disc, and
thus of any jet it could drive. In some conditions the precession rate is
uniform, and as a result the disc settles into a warp mode. The tidal torque
also leads to the truncation of the disc, to the evolution of the inclination
angle (not necessarily towards alignment of the disc and orbital planes) and to
a transport of angular momentum in the disc. We note that the spectral energy
distribution of such a warped disc is different from that of a flat disc. We
conclude by listing observational effects of warps in protostellar discs.
