Binga, like many tortoiseshell cats, is mostly black.
Did you know that tortie cats who are mostly black usually have a brindle (all-mixed-up) color pattern, and that the more white they have, the more likely the colors will be in patches instead of blended together? You can see this in many of my friends. Isabella of Beaded Tail, is a mostly-black tortie like Binga is (except that Isabella has a much nicer temperament!), while the tortoiseshell-and-white Spats of the Taylor Catsssss has way more color patches. And when torties are mostly-white, in the United States we refer to them as calico. Harlot, the cat before me, was a calico. And when the black is more gray and the red or orange is more of a peach hue, whether tortie or calico, they are called “dilute” (as in the color is diluted). My pal Willow is a dilute calico. Then there are exceptions to the rule — the lovely Sweet Praline is a tortie who is not mostly black. She is mostly a creamy beige color, and quite special!
The whole tortoiseshell phenomenon has to do with chromosomes, but I won’t go into all the science. If you want to read more about it, you can read the Wikipedia page about torties.