In physics, fields describe the distribution of forces in space. Their description thus requires the knowledge of magnitude and direction. Both are expressed through field contours; field forces act in the direction of the contours, and the distance between the contours indicates their magnitude. (The closer the contours are together, the larger the force.)
In an electric field the direction of the field is given by the electric charge of the charged sources. If the charge is negative, the field is directed toward the charge. All electric fields begin on a positive charge and end on a negative charge.
If two positive charges interact, their forces are directed against each other. This creates a repellent force as shown in the illustration. (The same occurs with two negative charges, because their respective forces also act in opposite directions.)
The electric field and resulting forces produced by two electrical charges of the same polarity. The two charges repel each other.
If a positive charge and a negative charge interact, their forces act in the same direction, from the positive to the negative charge. As a result opposite charges attract each other:
The electric field and resulting forces produced by two electrical charges of opposite polarity. The two charges attract each other.