Manipulate

Make anything interactive.

This draws a polygon with five corners:

In[]:=
Graphics[Polygon[CirclePoints[5]]]
Out[]=

Make the number of corners interactive with
Manipulate
. Replace the fixed number 5 with the variable n, wrap the expression with
Manipulate
, and
specify that n ranges from 3 to 12 in steps of 1, with an initial value of 5. Drag the slider to change the number of corners:

In[]:=
Manipulate[​
​Graphics[Polygon[CirclePoints[n]]],​
​{{n,5},3,12,1}​
​]
Out[]=
​
1.
Add as many controls as you want:

Add a control for the size of the polygon:

In[]:=
Manipulate[​
​Graphics[Polygon[CirclePoints[s,n]],PlotRange2],​
​{{n,5},3,12,1},​
​{{s,1},0,2}​
​]
Out[]=
​

Add a control for the color:

In[]:=
Manipulate[​
​Graphics[{c,Polygon[CirclePoints[s,n]]},PlotRange2],​
​{{n,5},3,12,1},​
​{{s,1},0,2},​
​{c,Red}​
​]
Out[]=
​
2.
Add labels to the controls:

Add labels to the controls after the initial values:

In[]:=
Manipulate[​
​Graphics[{c,Polygon[CirclePoints[s,n]]},PlotRange2],​
​{{n,5,"corners"},3,12,1},​
​{{s,1,"size"},0,2},​
​{{c,Red,"color"},Red}​
​]
Out[]=
​