The main idea of quantum mechanics is that an object like an electron or a photon behaves as both a particle and a wave… The other weird characteristic of quantum particles is that they can exist in multiple places at once, a phenomenon called superposition. But superposition is a fragile state. The moment that scientists try to measure the particles, the superposition state collapses and the particles come to exist in only one spot. Before the particles are disturbed, they exist in multiple places all at once.
Quantum entanglement is superposition on a larger scale… Particles become entangled when they interact with each other. Entanglement means that when an action is performed on one particle, it directly affects that particle's entangled partner no matter how far apart they are.