Vector quantities are physical quantities having both magnitude and direction. Magnitude is the size or amount of a quantity, and the direction is the orientation in space. For example, to open a door, a certain amount of force is applied in a particular direction. Hence, force is a vector quantity. The weight of any object, which is the force exerted on a body due to gravity, is a vector quantity. Vectors are represented as boldfaced italicized letters with an arrow above them. The magnitude is indicated with the same vector symbol between vertical bars or using italicized letters. Geometrically, vectors are shown using a line with an arrow pointing its direction and length indicating its magnitude. The displacement of an object from points A to B is shown with an arrow originating at A and ending at B and the vector is denoted as vector DAB. Two vectors are equal if they have the same magnitude and direction. The negative of a vector is obtained by reversing its direction. If two vectors point in the same direction, they are parallel. If they point in opposite directions, they are antiparallel.