Quantum entanglement is a physical phenomenon occurring when two or more quantum particles become linked in such a way that they share the same existence, regardless of the physical distance separating them. Measuring a quantum property, such as the spin or polarization, of one particle instantaneously influences the corresponding property of the other particles in the linked set. This correlation is stronger than what is permitted by classical physics and is one of the most counter-intuitive concepts in quantum mechanics. The existence of entanglement suggests a non-local connection between particles, forming the basis for advanced information technologies, including quantum computing and quantum cryptography, which exploit these correlations to process and secure data.