what is hamburger?

Hamburger also called by other people as burger, it's made of ground beef, onion, salt, ketchup, black pepper, dried oregano, egg, Worcestershire sauce,and grated cheddar cheese. The uncooked burger is called the patty. If it's a regular burger, it's the patty, ketchup, mayo with pickle. While hamburger, it's the same as burger. Some burgers have different weight, toppings, size and sauce, thus their names differ from regular one.

I would say popularity has to do with publicity. As for hamburgers, I understand it is the same as a burger (short for the other). I prefer homemade ones as I know what it is inside. They taste a lot different.