Scattering off a diatomic molecule, computer simulation. Credit: Eckart Wrede, University of Durham.
Forward scattering is the scattering of photons (particles of light or other forms of electromagnetic radiation) by a medium in such a way that most of the photons end up traveling in roughly the direction they started. More generally, it is scattering in which the angle between the initial and final directions of motion of the scattered particles is less than 90°.
Forward scattering is always accompanied by some backscattering (scattering in a generally backward direction), the proportion of the former increasing with particle size.