Every computer has millions, if not billions, of transistors in it. These transistors have one use, to control the flow of electricity. They act as a switch, but without any physical moving parts. Their size is incredible, since they work to allow electricity through on the atomic level, rather than a larger scale. The physical makeup of a transistor allows it to prevent the flow of electricity in one state, but when a small positive voltage is applied to the side, it allows the electricity to flow freely through it. Because of how small we are capable of making these transistors, we are beginning to run into issues that don't make much sense, like electrons jumping through a closed transistor. This comes as a result of quantum physics, and its seemingly random nature. If this weren't the case, transistors would continue to decrease in size until they were mere atoms in length. Even now, we are capable of creating incredibly tiny circuits, so much so that a small processor about an inch and a half wide can house upwards of 7.5 billion of them. If we allowed them to get smaller, data would become corrupt, as a single change in a 1 or 0 in a binary code can have catastrophic results.