The official definition of a vector is that it is a quantity that has both the characteristics of magnitude and direction. A common example of a vector is velocity. If you are in a car and the car is parked, then you have only the characteristic of position (the current point where your car is parked). But if you are in that same car and you are going down the road at a constant speed, you have two characteristics. You have your current position at a given moment in time, and you have the rate at which that position is changing (velocity). And this other characteristic of velocity is represented by a vector. You are going 60 mph (miles/hr) or 90 km/h. That is the magnitude of your speed, but we also need to know the direction you are going. This is where the use of vector comes into use. By drawing a vector in the direction you are going with the tail of the arrow located at your current location, and by sizing the length of the vector to represent the magnitude of your speed, we can use a vector to represent both the magnitude of your speed and the direction you are traveling. And by drawing the vector arrow starting with its tail at your current location we can combine that information to calculate your location at a future moment in time. So in summary a scalar (such as position or speed) only tells us one thing, it tells us the magnitude of your property such as speed or your current location, but a vector drawn with the tail at your current location or value, allows us to compute your future value by combining the information as described above.