Superfluidity is a state of matter where fluid or a liquid can act very strangely.
Some of the things a superfluid can do are:
It can flow extremely easily. (How easily a liquid can flow is called its viscosity.) In fact, it flows so easily that friction does not change the way it flows; it has zero viscosity. Because of this, it can actually flow out of a container, like a bowl, even when the bowl is not tipped so the liquid can spill out. It stays still when its container is spun, instead of starting a whirlpool like when a sink full of water is drained. However, a whirlpool does form if the container is spun at and above a certain speed.
So far, scientists have only been able to create superfluids at extremely cold temperatures. However, superfluids have quite a few uses in science today, like:
Superfluid Helium at nearly absolute zero -271.4 degrees Celsius [-456.2 degrees Fahrenheit] was used in a special satellite in 1983 to get information on infrared waves in space. Superfluids can be used in gyroscopes, to help machines predict information about gravity movements that can't be picked up with regular instruments only. One kind of superfluid was used to trap and slow down a beam of light from its normal speed of 670,600,000 mph (1,079,000,000 km/h) to only 38.03 mph (62.2 km/h) That means the beam of light was moving at .00000567104 % of its speed in a vacuum, or 17 million times slower.
There is also another state of matter called a supersolid, although how they are formed is more complex.