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Tkinter is Python's de-facto standard GUI library and ships with every CPython install. It's a thin Python layer over the Tcl/Tk toolkit, which has been around since 1991 and powers everything from the IDLE editor to thousands of small desktop tools. Tkinter is the easiest way to put a window, a button, and a callback together in a few lines of Python — no extra dependencies, no project scaffolding, no event-loop boilerplate beyond mainloop().
Every Tkinter program starts by creating a root Tk window, adding widgets to it, and calling mainloop() to start the event loop. mainloop() blocks until the user closes the window — anything after it only runs on shutdown.
import tkinter as tk
root = tk.Tk()
root.title("My App")
root.geometry("400x300") # width x height
root.minsize(200, 150) # don't allow shrinking past this
root.resizable(False, False) # lock the size entirely
root.mainloop()
Widgets are the building blocks of every Tkinter UI — labels, buttons, entries, checkboxes, text areas, listboxes, and more. Each widget is created with the parent window or frame as its first argument and made visible with a geometry manager (pack, grid, or place).
import tkinter as tk
root = tk.Tk()
# Static text
tk.Label(root, text="Name:", font=("Arial", 12)).pack()
# Single-line input
entry = tk.Entry(root, width=30)
entry.pack()
# Button with a callback
def greet():
print(f"Hello, {entry.get()}!")
tk.Button(root, text="Greet", command=greet).pack()
# Checkbox bound to a variable
agree = tk.BooleanVar()
tk.Checkbutton(root, text="I agree", variable=agree).pack()
# Multi-line text
text = tk.Text(root, height=5, width=40)
text.pack()
root.mainloop()
Tkinter has three geometry managers. Pick one per container — mixing pack and grid inside the same parent will hang the program.
import tkinter as tk
root = tk.Tk()
# pack — stack widgets in one direction
tk.Label(root, text="Top").pack(side="top", fill="x")
tk.Label(root, text="Bottom").pack(side="bottom", fill="x")
tk.Label(root, text="Center", bg="lightblue").pack(expand=True, fill="both")
# grid — row/column layout (use in its own frame)
form = tk.Frame(root)
form.pack()
tk.Label(form, text="Email:").grid(row=0, column=0, sticky="e", padx=5, pady=4)
tk.Entry(form).grid(row=0, column=1)
tk.Label(form, text="Password:").grid(row=1, column=0, sticky="e", padx=5, pady=4)
tk.Entry(form, show="*").grid(row=1, column=1)
# place — absolute pixel positioning (rarely the right choice)
# tk.Label(root, text="Pinned").place(x=10, y=10)
root.mainloop()
Buttons take a command callback for the simple case. For everything else — keypresses, mouse clicks on arbitrary widgets, resize events, focus changes — use bind() with a Tk event sequence.
import tkinter as tk
root = tk.Tk()
canvas = tk.Canvas(root, width=300, height=200, bg="white")
canvas.pack()
def on_click(event):
canvas.create_oval(event.x - 5, event.y - 5,
event.x + 5, event.y + 5, fill="red")
def on_key(event):
print("Key pressed:", event.keysym)
canvas.bind("<Button-1>", on_click) # left click
root.bind("<Key>", on_key) # any keypress
root.bind("<Escape>", lambda e: root.quit())
root.mainloop()
Common event sequences: <Button-1> (left click), <Button-3> (right click), <Double-Button-1>, <Motion>, <Enter> / <Leave>, <Key>, <Return>, <Configure> (resize).
Tk variables let you share state between widgets — set the variable, every widget bound to it updates automatically.
import tkinter as tk
root = tk.Tk()
name = tk.StringVar(value="World")
tk.Entry(root, textvariable=name).pack()
tk.Label(root, textvariable=name, font=("Arial", 20)).pack()
# The label updates live as the user types.
tk.Button(root, text="Reset", command=lambda: name.set("World")).pack()
root.mainloop()
Canvas is Tkinter's free-form drawing surface. Use after() to schedule the next animation frame — never use time.sleep() in a GUI app, it freezes the event loop.
import tkinter as tk
root = tk.Tk()
canvas = tk.Canvas(root, width=400, height=300, bg="black")
canvas.pack()
ball = canvas.create_oval(180, 130, 220, 170, fill="cyan")
dx, dy = 4, 3
def step():
global dx, dy
canvas.move(ball, dx, dy)
x1, y1, x2, y2 = canvas.coords(ball)
if x1 <= 0 or x2 >= 400: dx = -dx
if y1 <= 0 or y2 >= 300: dy = -dy
root.after(16, step) # ~60 fps
step()
root.mainloop()
tkinter.ttk gives you native-looking buttons, comboboxes, progress bars, treeviews, and notebooks. For anything more polished than a quick prototype, prefer ttk widgets.
import tkinter as tk
from tkinter import ttk
root = tk.Tk()
ttk.Style().theme_use("clam") # 'clam', 'alt', 'default', 'classic'
ttk.Button(root, text="OK").pack(pady=4)
ttk.Combobox(root, values=["Python", "Go", "Rust"]).pack(pady=4)
ttk.Progressbar(root, length=200, mode="determinate", value=70).pack(pady=4)
# Notebook (tabs)
nb = ttk.Notebook(root)
nb.add(ttk.Frame(nb), text="Tab 1")
nb.add(ttk.Frame(nb), text="Tab 2")
nb.pack(expand=True, fill="both")
root.mainloop()
Tkinter ships with ready-made message and file dialogs — useful when you don't want to build a custom modal.
from tkinter import messagebox, filedialog, simpledialog
messagebox.showinfo("Title", "It worked!")
messagebox.askyesno("Confirm", "Delete this file?")
path = filedialog.askopenfilename(filetypes=[("Text files", "*.txt")])
save_to = filedialog.asksaveasfilename(defaultextension=".txt")
name = simpledialog.askstring("Name", "What's your name?")
age = simpledialog.askinteger("Age", "How old are you?", minvalue=0, maxvalue=120)