Quantum Superposition is a fundamental principle of quantum mechanics that describes how a quantum system can exist in multiple states at once. For example, a particle like an electron can be in different positions or have different energies simultaneously until it is measured, at which point it 'collapses' into one of the possible states. This phenomenon is famously illustrated by Schrödinger's Cat, a thought experiment where a cat in a box is both alive and dead until someone opens the box to observe it. Quantum Superposition challenges our classical understanding of reality, suggesting that the universe is far more complex than it appears.