Foie gras de canard (fattened duck liver) is the liver of a duck that has been force fed to become fat. Particularly its liver gets abnormally enlarged.
The one in the picture has been pan fried with garlic in duck fat. Salt is only added right before consumption. It can be eaten hot or cold.
While foie gras has been around for thousands of years as a food item, it has recently been vilified by animal rights activist, who claim that the production of foie gras involves unnecessary cruelty to ducks or geese.
I grew up in a semi-rural environment where people still kept their fowl in their back yards. Most ducks and geese were fattened by force feeding them (usually by hand without the use of a gavage) before they were considered ready for slaughter and consumption. For most part of human history it was considered self evident that animals needed to be properly fattened before slaughter to improve the quality of their meat, and only the hysterical lipophobia based on pseudo science has shifted the demand towards lean rather than fat meat over the last few decades.
While the Internet is full of horrific pictures of ducks or geese being tortured by force feeding, I do not recall ever seeing force fed fowl showing signs of being any more unhappy than other livestock.
In fact I have seen a medium sized egg farm where all the hens had their beaks truncated in a grotesque fashion so that they would not peck each other to death in their crammed living space. Quite unnatural, and they looked far worse off than force fed ducks or geese, yet one rarely sees animal rights activists agitating against the consumption of eggs.
Fortunately the whole world has not gone insane just yet:
Just relax, and enjoy your foie gras, and remember that fat is your friend.