How do I display tooltips in Tkinter?

A simple solution in Python 3.7+

import tkinter as tk
from idlelib.tooltip import Hovertip
    
app = tk.Tk()
myBtn = tk.Button(app,text='?')
myBtn.pack(pady=30)
myTip = Hovertip(myBtn,'This is \na multiline tooltip.')
app.mainloop()

Though there are multiple answers, I'll add my 2 cents.

class ToolTip:
    def __init__(self,widget,text=None):

        def on_enter(event):
            self.tooltip=tk.Toplevel()
            self.tooltip.overrideredirect(True)
            self.tooltip.geometry(f'+{event.x_root+15}+{event.y_root+10}')

            self.label=tk.Label(self.tooltip,text=self.text)
            self.label.pack()

        def on_leave(event):
            self.tooltip.destroy()

        self.widget=widget
        self.text=text

        self.widget.bind('<Enter>',on_enter)
        self.widget.bind('<Leave>',on_leave)

This is a basic tooltip that will be displayed relative to the position of the cursor.

from tkinter import *
from tkinter.tix import *
root = Tk()
btn1 = Button(root, text="hello")
btn1.grid(row=0, column=0)
balloon = Balloon(root, bg="white", title="Help")
balloon.bind_widget(btn1, balloonmsg="Click to Exit")
root.mainloop()