Tkinter Hello world in Python

gistfile1.py

from Tkinter import *

def hello():
    """Callback function for button press."""
    print "Hello World"

# Main root window 
root = Tk()

# A button with a callback function
Button(root, text="Press here", command=hello).pack()
# .pack() method is necessary to make the button appear

# Event loop
root.mainloop()