In the last few decades, the causes of electrical phenomena have been accurately determined, and due to this, electricity is used to perform many useful functions. Today, electricity is so common that its use is taken for granted. Without it there would be no refrigerators, electric irons, electric lights, radios, televisions, or any other modern electrical equipment. Without electricity, life as modern man and woman know it could not exist. This chapter covers the fundamentals of electricity and provides coverage of basic electrical theory at a level that is easily understood by students who do not have a thorough knowledge of mathematics. A thorough study of this material will provide test takers with a solid foundation of questions and problems that may appear on the electrical theory part of the examination.