Conventional current

Note: current was determined to be a flow because it divided at a junction and recombined to the same value.

There was, from Volta's time onwards, for one hundred years (1800-1900), no understanding of what was flowing. An arbitrary direction choice was made. Current was defined as a flow of positive charge from the copper terminal of a zinc-copper battery. We now know that negative electrons flow from the negative terminal but the original definition has not been changed.

Ions may be positive or negative; we imagine the absence of an electron in a semiconductor to be a positive hole flowing in the opposite direction to electron flow, there is no compelling reason to reverse the original choice.