scaleA scale widget is for displaying an adjustable slider.  As the slider is
moved its value, which is displayed next to the slider, changes.  To
specify a scale, it must have -from and -to attributes,
which is the range of the scale. It can have a -command option,
which is set to a script to evaluate when the value of the slider
changes.
   
An example of a scale widget is:
     scale .s -from 0 -to 100
     
which creates a scale widget with name .s that will slide over a
range of integers from 0 to 100.
   
There are several other options that scales can have.  For example it is
possible to display tick marks along the length of the scale through the
-tickinterval attribute, and it is possible to specify both vertically
and horizontally displayed scales through the -orient attribute.