Tkinter reference: a GUI for Python

You can use a string specifying the proportion of red, green, and blue in hexadecimal digits:

For example, "#fff" is white, "#000000" is black, "#000fff000" is pure green, and "#00ffff" is pure cyan (green plus blue).

You can also use any locally defined standard color name. The colors "white", "black", "red", "green", "blue", "cyan", "yellow", and "magenta" will always be available. Other names may work, depending on your local installation.