Normally, we think of a variable as being a real number. In other words, if
our variable is called x, we write `` 
'' (read: x is an
element of the real numbers, whose symbol is 
.) This means that
x can take on the value of any real number between 
and 
.
But it only gets to be one number. This is fine for some things, but
there are many quantities that can not be completely described by just one
number. A vector is an object that holds a list of information, ie. several numbers.
As an example, think of the weather. If we were to describe the weather on any given day by just one number, what would it be? Average temperature? High temperature? Humidity? Wind speed? Cloud cover? It's pretty obvious that a complete description of the weather should include all of these and more. It would be convenient if we could define one object that would hold all of this information. We could then have a different weather vector for each day of the year.