Materials that do not allow electric current to pass through them.
In our household connections copper wires are covered with insulators to prevent the passage of current. All the cables and wires are covered with rubber insulation for our safety.
Without covering with insulators, it is not possible to leave the copper conductor as it is. If the positive and negative wires touch each other it may short circuit and large destruction will take place.
Switches are also made with insulators for our safety purpose. Insulators will not allow the passage of current and hence we are free from "Current Shocks".
Example 1: Why the people working with electricity are advised to wear rubber shoes?
Rubber is an insulator. It will not allow the current to pass through it. The people wearing the rubber shoes will not get electric shock.
Example 2: Why a person will not receive any shock when he stands very close to (not touching) a current passing wire without insulation?
The gap between person and the wire is filled with air, and air is a bad conductor of electricity, hence he will not absorb any shock.
In an insulator, internal electrons do not move freely. In an insulator the electrons are bound by the atoms tightly.
Insulator used to separate electrical conductors without allowing current to flow through them.
Insulators are used to wrap electric cables or other instrument, and it is called insulation.