AP photo chief Santiago Lyon has picked his top 10 photos of the year, or, more precisely, "10 representative photos from some of the biggest stories of 2013." They range from the Boston Marathon bombings to Nelson Mandela's funeral to the selection of Pope Francis. "The choice of these photos is meant only to represent the broader spectrum of human experiences captured in all the other images," writes Lyon. "Every experience is, in some way, a valid one." (More photography stories.)