For example, you may wish to bind a key to a button. This helps you streamline the control of an application. If you just have two input methods there could be a problem with things like arrows and backspace or delete messing up the calculator window.

import tkinter as tk
from tkinter import ttk

def press_eq(event):
    print('Equals key pressed.')

root = tk.Tk()

button1 = ttk.Button(root, text='=')
button1.bind('<Return>', press_eq)


button1.focus()
button1.pack(expand=True)

root.mainloop()

import tkinter

root = tkinter.Tk()

def right_click_handler(event):
    # event.num == 2 is MOUSE.
    if event.num == 2:
        print("RIGHT CLICK")

root.bind("<Button-1>", lambda x: print("LEFT CLICK"))
root.bind("<Button>", right_click_handler)

root.mainloop()

Here, a lambda is used to handle left clicks with <Button-1> while the more general <Button> handles both left and right, but uses

event.num == 2

to determine right click vs. left click, so it could handle both if needed.