Original: In the standard order of the canonical gospels, John is fourth, after the three interrelated synoptic gospels Matthew, Mark and Luke. In the earliest surviving gospel collection, Papyrus 45 of the 3rd century, it is placed second in the order Matthew, John, Luke and Mark, an order which is also found in other very early New Testament manuscripts.
Simplified: The Gospel of John is the fourth book of the New Testament, after the gospels of Matthew, Mark and Luke.