One of Vince Zampella's crowning achievements was the creation of the Call of Duty franchise, which has sold more than half a billion games worldwide.

Photographs help us look back on the moments that defined the year. Taken by NPR photojournalists nationwide, this collection goes beyond the headlines to reveal quietly powerful human stories.

Scientists have developed an experimental way to study how human embryos implant in a uterus, which may provide new insights into why miscarriages occur and how they can be prevented.