Color transparency arises from the behavior of quarks inside hadrons. These quarks are held together by the strong interaction, mediated by gluons. At high energies, when a high-energy hadron -or more generally a color singlet object interacts with a nucleus, it can propagate in the nucleus with less scattering than expected. This reduced scattering, or transparency, is attributed to the fact soon after the hadron is created, the gluon cloud surrounding the quarks is more compact, viz the effective size of the singlet object is small, leading to reduced interaction. This effect is observed in experiments involving high-energy electron scattering off nuclei, where the transparency increases with increasing energy of the incoming particles, or more precisely with the 4-momentum transfer Q between the accelerated particle beam and target nucleus.