Quantum entanglement is a phenomenon where two or more particles become linked, such that the state of one particle instantly influences the state of the other, no matter the distance between them. According to **quantum mechanics**, entangled particles share a single quantum state, and their properties, like spin or polarization, are correlated. This means that measuring one particle's property instantly determines the corresponding property of the other. Entanglement challenges classical notions of locality and has been described by Einstein as "spooky action at a distance." It plays a key role in quantum computing and quantum communication, offering potential for faster, more secure data transmission.