How to use an image for the background in tkinter?

One simple method is to use place to use an image as a background image. This is the type of thing that place is really good at doing.

For example:

background_image=tk.PhotoImage(...)
background_label = tk.Label(parent, image=background_image)
background_label.place(x=0, y=0, relwidth=1, relheight=1)

You can then grid or pack other widgets in the parent as normal. Just make sure you create the background label first so it has a lower stacking order.

Note: if you are doing this inside a function, make sure you keep a reference to the image, otherwise the image will be destroyed by the garbage collector when the function returns. A common technique is to add a reference as an attribute of the label object:

background_label.image = background_image