Curie Temperature is the temperature at which a ferromagnetic or a ferrimagnetic material becomes paramagnetic. A ferromagnetic material is one in which the individual magnetic moments of the atoms get aligned in the presence of an external magnetic field.
When the temperature is raised above the curie temperature, the thermal agitation of the atoms result in the random alignment of the individual magnetic moments. This results in the material becoming paramagnetic. A ferromagnetic material which is above its curie temperature will not be attracted by a magnet.
Check out this video to see a ferromagnetic material which is above the curie temperature get attracted by a magnet as soon as it cools below the curie temperature.
The Curie Temperature is also known as the Curie Point.
The Curie Temperature is used in storage devices such as magneto-optical storage systems to erase and form new memory.