The charge, within a wire is a flow of electrons.
“Basically” There are 2 types of charge flow there are two kinds of charge flowing (1) by electrons, and (2) as Ions.
The first occurs mainly in solid conductors , while the second one is a chemical process that occurs in liquid electrolytes.
Wires are typically comprised of metals with free electrons inside their Valance shells. Free electrons are able to move with random motion when they are unbiased, i.e. there is there is no voltage (potential or more precisely) different is applied across the ends. The random motion makes the net movement of the device zero.
If a potential difference applies between two sides free electrons are drawn towards the positive terminal, leading to an inverse movement toward the same.
Since electrons are negatively charged particles their movement is also referred to as charge flow.