Ground coffee is what most Americans grew up with. Open up a big can and scoop it into the coffee maker, usually a drip coffee maker. If you are really old, or go camping, you may use a percolator. If you own a French Press, ground coffee is a must.
While it is possible to grind your own, see Whole Beans, most people opt for the convenience of letting the manufacturer grind their coffee.
Nowadays, I find myself getting my favorite ground coffee in a bag and loading it into a refillable K Cup for my Keurig single serve machine. This way I can get great coffee that I can’t find preloaded and I save some money as well!
However you make your coffee, ground coffee will surely be with us well into the future.