Canvas

Canvas is a widget that lets you to draw on, following program demonstrates how to draw some basic shapes

import tkinter


base = tkinter.Tk()
base.title("canvas example")
canvas = tkinter.Canvas(base, bg="white", height=250, width=300)
canvas.pack()

canvas.create_line(0, 100, 100, 100, fill="black") #x, y to x, y
canvas.create_oval(10, 10, 50, 50, fill="red", outline="green")
canvas.create_oval(100, 100, 150, 150, outline="green")
canvas.create_polygon(0, 100, 100, 150, 200, 250, outline="green", fill="white")

points = [100, 140, 110, 110, 140, 100, 110, 90, 100, 60, 90, 90, 60, 100, 90, 110]
canvas.create_polygon(points, outline="black",fill='yellow', width=3)


canvas.create_line(0, 0, canvas["height"], canvas["width"], fill="black") #x, y to x, y
base.mainloop()

Painting using ovals example from http://www.python-course.eu/tkinter_canvas.php

from tkinter import *

canvas_width = 500
canvas_height = 150

def paint( event ):
   python_green = "#476042"
   x1, y1 = ( event.x - 1 ), ( event.y - 1 )
   x2, y2 = ( event.x + 1 ), ( event.y + 1 )
   w.create_oval( x1, y1, x2, y2, fill = python_green )

master = Tk()
master.title( "Painting using Ovals" )
w = Canvas(master, 
           width=canvas_width, 
           height=canvas_height)
w.pack(expand = YES, fill = BOTH)
w.bind( "<B1-Motion>", paint )

message = Label( master, text = "Press and Drag the mouse to draw" )
message.pack( side = BOTTOM )
    
mainloop()

With clear button

from tkinter import *

canvas_width = 500
canvas_height = 150

def clearall():
	w.delete("all")

def paint( event ):
   python_green = "#476042"
   x1, y1 = ( event.x - 1 ), ( event.y - 1 )
   x2, y2 = ( event.x + 1 ), ( event.y + 1 )
   w.create_oval( x1, y1, x2, y2, fill = python_green )

master = Tk()
master.title( "Painting using Ovals" )
w = Canvas(master, 
           width=canvas_width, 
           height=canvas_height)
w.pack(expand = YES, fill = BOTH)
w.bind( "<B1-Motion>", paint )

message = Label( master, text = "Press and Drag the mouse to draw" )
message.pack( side = BOTTOM )
button = Button(master, text="Clear", command=clearall) 
button.pack(side=BOTTOM)   
mainloop()