The idea of an electric field explains why charged objects push and pull on each other without touching. A charged object has an electric field around it. A second charged object placed in that field feels a force from it. If the objects have the same type of charge they repel, and if they have opposite charges they attract. This is how a charged balloon can move a hanging charged rod from a distance.
The field also explains why a charged object can attract an uncharged insulator. The field of the charged object makes the charges inside the other object shift very slightly, so that one side becomes a little positive and the other side a little negative. The side nearer the charged object has the opposite charge, so it feels a larger attraction than the repulsion on the far side. This is why a rubbed balloon sticks to a wall or picks up small pieces of paper.
In a simple investigation, a charged rod is hung from a thread and a second charged rod is brought close. If the rods repel, they have the same charge. If they attract, they have opposite charges. The force is larger when the rods are closer, because the field is stronger there.