Final answer:
Substances that enhance the flow of current are called conductors, those that inhibit current flow are insulators, and those with variable conductivity properties are called semiconductors.
Step-by-step explanation:
Substances that enhance the flow of current are called conductors. Substances that inhibit the flow of current are known as insulators. Substances that neither conduct nor inhibit well are called semiconductors.
Materials like metals and salty water, which have free electrons or ions, fall into the category of conductors. These allow charges to move through them with relative ease. In contrast, materials such as glass and rubber do not allow charges to move freely through them because the electrons are bound in their structures, making them insulators. Finally, semiconductors have a unique property where their conductivity can be altered under certain conditions, making them critical in the manufacturing of electronic devices like computer chips.