Locality in physics refers to the principle that objects can only influence each other through direct interactions, exemplified by a billiard ball striking another. Historically, this concept dominated scientific thought until the 20th century. Non-locality challenges this notion, suggesting that particles can affect one another without direct interaction, as seen in quantum entanglement. In this phenomenon, a change in one entangled photon instantaneously impacts its partner, regardless of distance. Understanding these concepts is crucial for grasping advanced topics in quantum physics.