An apple is suspended by a string. The string is stretched due to the weight of the apple. The forces acting on it are; the weight of the apple acting vertically downwards and the tension in the string pulling it vertically upwards. The two forces are parallel but opposite to each other. These forces are called parallel forces.

In the figure, Forces F₁ and F₂ are also unlike parallel Forces, because they are parallel and opposite to each Other. But F₁ and F₂ are not acting along the same line and Hence, they are capable to rotate the body.