To create a superfluid, you must cool a substance to an extremely low temperature. The most common example is the liquid isotope known as helium-4. When scientists cool liquid helium-4 below a specific temperature called the lambda point, it transforms.
It completely stops behaving like a normal liquid and starts following quantum physics rules. In this new state, the fluid has absolutely no viscosity or thickness. Normal liquids always experience some internal friction as their molecules rub against each other.
A superfluid completely lacks this friction and flows without any resistance at all. This lack of friction leads to several highly bizarre visible behaviors. For instance, a superfluid will spontaneously form a thin film and creep up walls.
It will literally climb out of an open glass cup to escape its container. Furthermore, if you slowly rotate a cup containing a superfluid, the liquid stays totally still. It does not spin with the cup because there is no friction to drag it along.
Students often confuse a superfluid with a normal gas because both move so easily. However, a superfluid is definitely a liquid that just happens to share one quantum state. It behaves as a single giant quantum object rather than many separate bouncing atoms.