When first starting to study electrical theory, there are some basic questions that first come to mind: what is electricity, how is a current produced, and what do we mean by the words electric charge, voltage, and electric potential? The first to deal with these matters were the famous scientists of the 19th century: Nikola Tesla, Thomas Edison, Ernst Werner von Siemens, Alexander Graham Bell, Lord Kelvin, and many more. These people actually set the basis for the electrical science and engineering that ultimately changed our modern way of life.
To begin with, terms such as electricity, electric charge and electric field require a basic knowledge of atomic theory. Subatomic particles (electrons and protons) are considered to be the carriers of electric charge, an inherent property of these particles that also produces a field of forces around it known as an electric field. The resultant field exerts attractive or repulsive forces on any other charges placed within the field. The motion of these charges constitutes an electric current.
Read the following articles for an introduction to the basics, as well as the main terms of electrical theory, including: static electricity, resistance, voltage and electric potential, just to name a few.