>>12385286They don't exist in nature as far as we're aware. The Gauss' law for magnetism in Maxwell's equations ensures that.
However, there would be some interesting consequences if it were to exist. Dirac showed that the existence of magnetic charges would force electric charges to be quantized.
There are also some Grand Unification Theories (theories attempting to unify electroweak and strong forces) that predict the existence of magnetic monopoles.
