The word “electricity” is derived from the Greek word electron, meaning “amber." Scientists have determined that electricity seems to behave in a constant and predictable manner in given situations or when subjected to given conditions. Battery-supplied direct current electricity has many applications and is widely used in household, commercial, and industrial operations. Soldering operations are a vital part of electrical and electronics maintenance procedures. Soldering is a manual skill that must be learned by all personnel who work in the field of electricity. A similar relationship holds for the electrical field; that is, magnetism and basic electricity are so closely related that one cannot be studied at length without involving the other. The electrician or student of electricity must be able to read electrical drawings to understand the system and to determine what is wrong when electrical equipment fails to run properly.