Per the AP: "The Norwegian Nobel Committee honored the Geneva-based group 'for its work to draw attention to the catastrophic humanitarian consequences of any use of nuclear weapons and for its ground-breaking efforts to achieve a treaty-based prohibition of such weapons.'"

Why it matters, from the NYT: "The Norwegian Nobel Committee's choice amounted to a blunt rejoinder to the world's nine nuclear-armed powers, which boycotted the negotiations and denounced the treaty as a naïve and dangerous diversion."