|I understand how computer information travels as bits from source to destination, but how does each bit travel through the wire at a molecular level? — JCC, Atlanta, Georgia
At the simplest level, a bit travels as a packet of positive or negative charge through a wire. To start this movement, the source injects a small amount of charge onto the end of the wire. Since like charges repel and opposite charges attract, this new charge pushes on charges further down the wire, and those charges push on charges still farther down the wire, and so on. Overall, a wave of forces and responses rushes along the wire until it reaches the destination end of the wire. There charges flow off the wire and into the destination device. While these charges aren't really the same ones that were put on the wire by the source, they have the same charge and one can imagine that charge has simply moved from the source device to the destination device by way of the wire. The destination device can examine this charge to determine whether the source was sending a 0 or a 1.