Hamburger meat or ground beef comes from the round, chuck and sirloin parts of the cow.
The meat that is cut from the round, chuck and sirloin parts of the cow are then ground up into hamburger meat or ground beef and is used for making hamburgers.
You may also see ground beef sold as ground chuck because that would be the chuck part of the cows meat ground up into ground beef so it's called ground chuck.
So ground beef or hamburger can come from several parts of the cow.
When it comes to hamburger the hamburger meat or ground beef is made from the less tender and less popular cuts of beef.
And those less popular cuts of beef and less tender cuts of beef are the chuck, sirloin and round cuts of meat from the cow.