To define this part of the electricity is not so easy and any definition is never finished. We all know that this part of the Physics tries to manipulate to way as one wants the step of the electric current. Then we might say that the Electronics is the science that studies the movement of the electrons inside the bodies semiconductors or drivers under certain conditions.
Any investigation begins on having had a problem, the principal problem was finding methods with which it was possible to do electricity. An important step happened on having discovered the matter of the electromagnetism, or, to make to turn spirals inside a magnetic field.
Little by little the electricity became universal and it was used in infinity of applications, but to use it with more precision inside his functions it was necessary to manipulate the electric current. On having invented the electromagnetic relay, it was possible to make happen or to interrupt big tensions of electric current, all this safely and with a minimal sag, but there were needed thousand different devices of contact, which were remaining affected by the blow of electricity, shown by the chispeo and the heat.
In the course of time one could be working with minor tensions and intensities what was allowing two important advances, work with less dangerous devices and save the consumption. After the waves were discovered hertzianas (with them that of the radio), it was necessary to manipulate the current to amplify, to receive, to select and to decode the sign that the waves were transporting. This gave birth to a branch of the electricity that is in charge of studying thoroughly the electrical phenomena (working with small elements and very small values) called Electronics.