In order to understand why semiconductors behave as they do, it is necessary to examine the atomic structure of elements, and how it affects their electrical properties. The number of protons and electrons in an atom, and the way in which they are ordered affects the electrical properties of the element. Elements in which electrons can move easily are known as conductors; those which have high resistance to the flow of electrical current are known as insulators; and then there is a small group of insulators which can be altered to become semiconductors. During the manufacturing process, semiconductors can be transformed into P-type or N-type semiconductor by the addition of other elements.