Define conductor, insulator, semiconductors

Conductor:

•  A conductor is a material that allows electricity to flow through it easily. 
• Metals such as copper and aluminum are good conductors of electricity.

Insulator: 

• An insulator is a material that does not allow electricity to flow through it easily. 
• Examples of insulators include rubber, plastic, and glass.

Semiconductor: 

• A semiconductor is a material that has electrical conductivity between that of a conductor and an insulator. 
• Examples of semiconductors include silicon and germanium. Semiconductors are used in electronic devices such as transistors and diodes.