I've been asked by someone with minimal background in physics to explain what vector and scalar quantities are and give examples. Here are my thoughts: A scalar is a quantity that has a magnitude only, it is completely specified by a single number. Importantly, it has no directional dependence and as such is invariant under rotations and reflections of coordinate systems. An example of a scalar is temperature. Indeed, the temperature at any given point in a region does not change if one measures it whilst facing north, or whether one measures it whilst facing south, or north-east, or indeed whilst facing any other direction, it simply has a numerical value at any given point. A vector is a quantity that has both a numerical value and a direction associated with it. Unlike a scalar, it has directional dependence. The direction of a vector can be quantified in terms of its components relative to the coordinate axes of a given coordinate system, with each component heuristically describing the amount that the vector points along each of the coordinate axes. The components of a vector are not invariant under rotations and reflections of coordinate systems, since they are relative to a particular coordinate system, therefore changing the coordinate system will change the components (intuitively, the coordinate axes of a coordinate system rotated relative to another will point in different directions than the unrotated coordinate system, and so the amount the vector points along each coordinate aside will change depending on the coordinate system). An example of a vector is the position of an object, for example the position of a car relative to a curb. One can describe its position whilst parallel to the curb facing the car or orthogonal to the curb facing away from the car, or indeed at any other angle the curb facing in any direction. Clearly the position of the car will depend on which reference frame (coordinate system) one measures it from. If one measures it whilst parallel to the curb facing the car then its position is parallel to a single axis of your coordinate system, whereas if one measures the position of the car at a 45 degree angle to the curb (facing the car for simplicity), then its position will have components along two axes of your coordinate system. Hence, the coordinate description of the cars position is not invariant under rotations and it is this a vector, having both magnitude (the distance from the observer to the car) and direction (the angle of car relative to the observer). I appreciate that this isn't a question as such, but any feedback, suggested improvements of the explanation, would be much appreciated.