Here's why:

* Structure: Rubber molecules are long chains with a lot of carbon and hydrogen atoms. These molecules don't have free electrons that can easily carry an electric current.

* Resistance: Rubber has a very high electrical resistance, meaning it resists the flow of electricity. This makes it an effective insulator.

* Applications: Rubber is used in many applications where electrical insulation is crucial, such as:

* Electrical wires and cables: The insulation around wires is often made of rubber to prevent electric shocks.

* Gloves and footwear: Rubber gloves and boots are used by electricians to protect them from electric shock.

* Electrical components: Rubber is used in many electrical components, such as switches and connectors, to provide insulation.

However, it's important to note that:

* Different types of rubber: Not all rubbers are created equal. Some types of rubber, like conductive rubber, are designed to conduct electricity.

* Conditions: Even regular rubber can become less effective as an insulator under certain conditions, such as high temperatures or exposure to certain chemicals.

Overall, rubber is a good insulator, but it's important to understand its limitations and choose the appropriate type of rubber for the specific application.