__(A) Definition of Vector and Vector Notation__**1.**Vector is a quantity that has both magnitude and direction.

**2.**Scalar is a quantity that has magnitude only.

**3.**A vector can be presented by a line segment with an arrow, known as a directed line segment.

__(B) Equality of Two Vectors__**1.**Negative vector of $\overrightarrow{AB}$ has the same magnitude as $\overrightarrow{AB}$ but its direction is opposite to that of $\overrightarrow{AB}$ .

**3.**Two vectors are equal if both the vectors have the same magnitude and direction.