Why do Mcdonalds call it a hamburger?

I've always wondered, why does McDonald's call their iconic sandwich a hamburger? Is it simply a matter of branding or is there more to the name? Could it be that the term 'hamburger' has some historical significance tied to the dish, or is it simply a common term that everyone recognizes? And what makes McDonald's hamburger stand out from the rest? Is it the patty, the toppings, or the way it's prepared? I'm eager to learn more about the origins of this name and what sets it apart in the fast-food industry.