Here's why:

* Atoms and Electrons: Insulators have tightly bound electrons. These electrons are not easily freed to carry an electrical current.

* Energy Gap: Insulators have a large energy gap between their valence band (where electrons reside) and conduction band (where electrons can move freely). This means a lot of energy is required to excite an electron to the conduction band, making it difficult for current to flow.

Examples of electrical insulators:

* Rubber: Used in electrical cords and gloves.

* Glass: Used in windows, light bulbs, and electrical equipment.

* Plastic: Used in many electrical components and packaging.

* Wood: Used in construction and furniture.

* Air: Acts as an insulator in many electrical applications.

Important Note: No insulator is perfect. Under high enough voltage, even the best insulators can break down and allow current to flow.