quantum entanglement
Quantum entanglement is a very mysterious and magical thing. It means that two or more particles can be connected together even when they are in different places. These particles "know" about each other and can act together as one. It's like having two pieces of a puzzle that fit together no matter how far away they are from each other. These pieces can come together and be part of one big picture!
Related topics others have asked about:
Bound entanglement,
Concurrence (quantum computing),
Controlled NOT gate,
ER = EPR,
Einstein's thought experiments,
Entanglement distillation,
Entanglement witness,
Faster-than-light communication,
John Clive Ward,
Multipartite entanglement,
Normally distributed and uncorrelated does not imply independent,
Pauli exclusion principle