Final answer:
Electric current in metal wires is due to the flow of electrons towards the positive terminal, with positive ions remaining fixed in place. The direction of conventional current is opposite to electron flow, a convention from Franklin's time.
Step-by-step explanation:
When an electric current is passed through a metal wire, the electrons, which are negative charges, move towards the positive terminal. This movement of electrons constitutes the electric current flowing through the metal. In contrast, the metal's positive ions, which are atoms that have lost some electrons, do not move along the wire; they stay relatively fixed in the metal lattice. The current direction we refer to in circuit diagrams and discussions is conventional current, which flows from the positive to the negative terminal, opposite to the actual electron flow. This convention dates back to Benjamin Franklin's time. While in metals only negative charges (electrons) move, in other conductive mediums like ionic solutions, both positive and negative charges may move.