For several weeks fans of the Person of Interest have been waiting to find out if Shaw is alive or dead. Last we saw her, it appeared that she sacrificed her own life to let her friends get away from the Samaritan group that was after them. But Root refused to believe that she was dead and she and John have been on a mission to find her.
Last nights episode (2/3/15) ended the suspense and answers the question. I won't spoil it here, so if you haven't seen it yet hop to it before you find out by mistake.
Picture of Sarah Shahi courtesy of Wipedia via CC 2.0