When a charged object touches an uncharged or neutral object, charge flows from higher density to lower density. This means that the charge flows from the charged object to the neutral object until both objects have a similar charge, according to the Physics Classroom.
When a neutral object gains electrons, it becomes negatively charged, and when it loses electrons, it becomes positively charged. A charged object has an excess of like charges, either negative or positive. When two or more like charges are in close proximity, the electrostatic force between the like charges causes them to repel and spread away from each other. This is accomplished through a flow of electrons.
When a negatively charged object, which has an excess of electrons, touches a neutral object due to the force of repulsion between the excess electrons in the charged object, the electrons tend to spread out into the neutral object until both objects have an equal charge density.
A positively charged object has a deficiency of electrons. When a positively charged object touches a neutral object, the positive charges attract electrons from the neutral object to decrease the number of positive charges in itself. The neutral object ends up with a net positive charge because its electrons are attracted by the positively charged object. The electron flow from the neutral to the positive object ceases once both objects have an equal charge density.