Conductivity is a physical property of a material that describes how resistant a material is to the flow of electrical current through it.

A conductive material will allow the flow of current (they have a low resistance/ resistivity). Examples include metals and graphite, which both have free electrons that can flow freely within the material.

A non-conductive material will impose resistance to flowing electrons. Collisions between atoms and electrons disrupt the current by dissipating some energy as heat. This is why circuits and electrical devices can become hot after operating for a long time.

A Cartoon showing the inside of a highly conductive wire and a highly resistive wire. Where the electrons are freely flowing within the highly conductive wire and the electrons are not able to freely flow within the resistive wire

Figure 1 - Electrons traveling through a wire made of a conductor and an insulator.