A simple example
Imagine Alice and Bob each receive one of two linked mystery coins. When Alice checks hers, the result is strongly connected with what Bob will find—even if Bob is very far away—but neither can use the coins to send a secret message instantly.
Go Deeper
Entangled particles are described by a shared quantum state, even when they are separated. When scientists measure one particle, the results are correlated with measurements of the other more strongly than classical physics allows. Experiments testing Bell’s inequalities have repeatedly confirmed these quantum correlations. Entanglement does not let Alice control her result or send information instantly to Bob, so it cannot be used for faster-than-light communication. It is nevertheless a real and powerful feature of nature, central to quantum computing, quantum cryptography, and experiments exploring the foundations of physics.