This chapter provides a brief overview of key concepts needed for understanding light propagation deep into a turbid medium, and parameters that are exploited to extract photons that remember initial properties and retain information for generating direct images of targets embedded deep inside the medium. It also provides an overview of the physics of light propagation through highly scattering turbid media, such as microspherical beads suspended in water, Intralipid-10% or similar suspensions, ex vivo tissues from brain, breast, prostate, and other body organs. Linear and nonlinear propagation of optical vortex beams in model turbid media and biological tissues (brain, breast, prostate) are then explored to assess their application in deep imaging application of human body. Ballistic photons are most effective in forming a shadow image. Snake photons also generate transillumination images whose resolution depends on the position and width of the temporal slide used in imaging.