Materials can be classified in terms of the ability of charges to move within an object:

 

 

Superconductors are materials that are perfect conductors  in which

electric charges move without any hindrance.      

                                                                                                               

Conductors are materials in which electric charges move relatively freely.

                   Metals: Cu, Al¡­ 

 

Insulators are materials in which electric charges do not move freely.

                Plastic, rubber ¡­¡­

 

Semiconductors are materials, their electrical properties are somewhere

between conductors and insulators, chargers can move somewhat freely,

but far fewer charges are moving.

Silicon, Germanium in computer chips