Every major scale has a kissin’-cousin — a relative minor scale. It is related to the major scale of the key, but begins on the 6th note of the major scale. For example, if I were to play the C major scale but instead of playing it from C to C I played it from A to A, that would be the A minor natural scale. What makes it related? It uses the same notes — just starts and ends at a different point.

To complicate the picture, there are 3 varieties of each minor scale: the natural minor scale, the harmonic minor scale, and the melodic minor scale. Please refer to this page on the web for audio samples of each type of minor scale: 3 kinds of minor scales
Then watch this short video on minor scales: