A 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.