What is a, b, c, and d in: rect1 = drawing.create_rectangle(a, b, c, d) and circle1 = drawing.create_oval(a, b, c, d)

[CrazyVideoGamez]

What is a, b, c, and d in:
from tkinter import *
window = Tk()
drawing = Canvas(window, height=500, width=500)
rectangle = drawing.create_rectangle(a, b, c, d)
and:
circle = drawing.create_oval(a, b, c, d)
???