Color transparency is a phenomenon observed in high-energy particle physics, where hadrons (particles made of quarks such as a proton or mesons) created in a nucleus propagate through that nucleus with less interaction than expected. It suggests that hadrons are first created with a small size in the nucleus, and then grow to their nominal size. Here, color refers to the color charge, the property of quarks and gluons that determines how strongly they interact through the nuclear strong force.