My 12th grade physics book on electrostatics says:
Potential difference between two points in electric field can be defined as work done in displacing a unit positive charge from one point to another against the electric forces.
By this logic, the potential difference between two points in an electric field should always be positive because the work done in moving a unit positive charge against the direction of electric field will always be positive. But potential difference can also be negative, so what exactly is my book describing?