According to the order by which we "get on" diatonic scales, we can determine the mode.
In our system we have two modes: major and minor.
Thus, we can point that the step from which the scale begins determines its name (C, D, E sharp, B, etc); this order determines the mode (major or minor).
The first note of the scale is called First degree, the second one Second degree, the third one Third degree, etc.