What is a Vector?

You're used to working with what is called scalar values. A scalar value is just a number. It has what we call a magnitude, or a number quantifying how big it is. Say, I walk 100 meters. 100 meters is a scalar value.

A vector has not only a magnitude, but also a direction. It describes not only how far, but also which way. I walk 100 meters north-west. This describes both a magnitude, how far I've gone, and a direction.

Vectors are written as a set of numbers, depending on how many dimensions the vector exists in. For a two dimensional vector, for example, it's two values, defining an X and Y. If you draw an arrow from the origin to the XY point on a graph, this is the vector. The length of the arrow is the magnitude and the direction that it points is the direction.

A unit vector is a special type of vector that has a magnitude of exactly one. It's useful for describing a direction.