The purpose of this review is to outline the systematic properties of radio jets on kpc scales, as derived from the basic observations of surface brightness and linear polarization and to emphasize the uncertainties in the determination of their physical parameters. These results come primarily from observations of about 100 jets with the VLA: a fuller account is given by Bridle (1982) and the proceedings of IAU Symposium 97 contain many illustrations and references, which must be omitted here.

I take a “jet” to be a feature in the radio brightness distribution which is at least four times as long as it is wide, which can be clearly separated (spatially or by brightness contrast) from the rest of the source and points away from a radio core. Wilson (1982) has considered jets in spiral galaxies and I shall discuss only the more luminous jets found in elliptical radio galaxies and quasars.