The property of “insulation” refers to a material’s ability to store as opposed to conduct electrical current.
An insulator is the opposite of a conductor. A good example of an insulator is a stone hearth. Although the hearth stores heat from a hot fire, it can be touched without danger because the heat is retained by the hearth and not transferred to the skin (as opposed to touching the metal grille on the same fireplace).
In the case of carpet construction, all fibers are insulators unless a conductive coating is applied to the external perimeter of the fibers. Insulated fibers will both generate and store static electricity. They cannot be grounded, even if a copper wire is attached to the tile.