Question

what is superconductivity ?

Answer 1

Superconductivity is a property of conductors at super low temperatures. When at super low (we mean really really low) temperatures, conductors can have /zero/ resistance. This allows for for some really awesome things.
Like this:
http://www.youtube.com/watch?v=GtRsGcAY26c

Answer 2

Superconductivity is a phenomenon in which the electrical resistance of a material abruptly drops to zero at very low temperatures. Superconductivity is exhibited by many non-conducting materials at room temperature. It is due to the interaction of cooper electrons with the phonons(lattice vibrations). Moreover cooper electrons are bosons