Q is, with the Gospel of Mark, one of the two major literary sources of the synoptic gospels, and is identified as material common to Matthew and Luke, but not in Mark. Unlike Mark, Q did not survive, inasmuch as most if not all of Q had been copied into Matthew and Luke. It is probably easiest to regard Q as an arbitrary symbol, though it is sometimes associated with the German word for source = Quelle. Click on Two Document Hypothesis for discussion.