The stream-disk interaction

I review theoretical aspects of the interaction between the accretion stream and the disk in interacting binary systems, concentrating on recent hydrodynamic calculations. At low accretion rates, cooling is expected to be efficient, and the interaction leads to a nearly ballistic stream overflowing the disk rim towards smaller radii. If cooling is ineffectual, the shocked gas produces a bulge on the disk rim, and there is no coherent stream inward of the disk edge. Results are presented for the mass fraction and velocity structure of the overflowing component, and the implications for X-ray observations of `dips', and doppler tomography of cataclysmic variables are briefly discussed.