Quantum tunneling is a quantum mechanical phenomenon where particles pass through an energy barrier that they classically shouldn't be able to. This phenomenon is essential in various fields of physics and chemistry, including catalysis. In classical mechanics, particles require energy equal to or greater than the height of the barrier to overcome it. However, due to the wave-like properties of particles in quantum mechanics, there is a non-zero probability that a particle can "tunnel" through a barrier even if it doesn't have the requisite energy.
