Superfluidity is a phase of matter that occurs at extremely low temperatures, where a liquid can flow without viscosity. This means it can move without losing energy, allowing it to flow through tiny openings and around obstacles effortlessly. The phenomenon is most commonly observed in liquid helium-4, which becomes superfluid below 2.17 Kelvin. In a superfluid state, the liquid exhibits unique properties, such as the ability to climb walls and form persistent currents. This behavior is a result of quantum mechanical effects, where particles, like helium atoms, behave collectively as a single quantum entity, leading to fascinating and counterintuitive behaviors.