Conductors are materials with many free electrons, so they allow electrical current to flow through them. Therefore, conductors are required in order to bring electricity to every room of the house.
Insulators, instead, are materials with few or no free electrons, so electrical currents do not flow through them. In the electrical wiring of the houses, they are used in order to isolate the conductive elements of the wire from other conductive materials (in fact, if the conductive elements touch other conductive elements of the house, part of the current would be dissipated)