True

Explanation:
Dielectric:
A dielectric is a material that does not conduct electricity easily and is used to separate the conductive plates of a capacitor. Dielectrics are substances that have a high resistance to the flow of electric current. When a dielectric is placed between the plates of a capacitor, it reduces the electric field and increases the capacitance of the capacitor.

Insulator:
An insulator is a material that does not conduct electricity. It has a high resistance to the flow of electric current. Insulators are used to prevent the flow of electric current and to provide electrical insulation in various applications.

Difference between a Dielectric and an Insulator:
Although both dielectrics and insulators do not conduct electricity easily, there is a subtle difference between the two:

- A dielectric is specifically used in the context of capacitors, where it is placed between the plates to increase the capacitance. Dielectrics are designed to have high permittivity, which is a measure of how easily electric fields can be established in a material.

- An insulator, on the other hand, is a broader term used to describe materials that do not conduct electricity. Insulators can be used in various applications to prevent the flow of electric current and provide electrical insulation.

Relationship between Dielectrics and Insulators:
Based on the definitions, it can be concluded that:

- A dielectric is always an insulator because it is specifically designed to have a high resistance to the flow of electric current. Dielectrics are one type of insulator that is used in capacitors.

- However, an insulator is not necessarily a dielectric. Insulators can be used in various applications where electrical conductivity needs to be avoided, but they may not be specifically designed to be used in capacitors or have high permittivity.

Conclusion:
In summary, a dielectric is always an insulator, but an insulator is not necessarily a dielectric. Dielectrics are a specific type of insulator designed for use in capacitors to increase capacitance. Insulators, on the other hand, can be used in various applications where electrical conductivity needs to be avoided.