Which material does not allow electric charges to flow easily?

An insulator is a material that does not allow electric charges to flow easily. This property is important in many practical applications, such as in electrical wiring, where insulation is necessary to prevent unwanted flow of current and to protect users from electrical shocks. Insulators typically have tightly bound electrons that do not move freely, making it difficult for electrical current to pass through.

In contrast, conductors, such as metals, have free electrons that facilitate the easy flow of electric charges. Loads are components of a circuit that consume electrical energy, and while they may affect the flow of electricity, they do not directly relate to the conductivity of a material. An electroscope is an instrument used to detect electric charge but does not classify as a material that influences the flow of charges in the same context as insulators or conductors.