A number line is a line that has points equally spaced.  Each point corresponds to a special number.  A number line can be used to count forward and backward.

     This number line shows counting forward.  You can tell by the direction of the arrow on the number line.  Counting forward moves you from smaller numbers to larger numbers. 1 is larger than 0, 2 is larger than 1, 3 is larger than 2, 4 is larger than 3, and so on down the number line as we count forward.

     The number line below shows counting backward.  Again you can tell by the direction of the number line arrow that counting backward takes you from larger numbers to smaller numbers.  9 is smaller than 10, 8 is smaller than 9, 7 is smaller than 8 and so on down the number line as we count backward.