The first three gospels are sometimes known as the "synoptic" gospels. What does this term mean, and how does it differentiate them from the gospel of John?
Matthew, Mark, and Luke are very similar: they record many of the same miracle stories, parables, and sermons. John by contrast has fewer miracles (and most are unique), no parables at all, and is the only Gospel to record Jesus's teaching on the nature of God at the Last Supper (ch. 13-17). Synoptic comes from the Greek for "see together" because they tell Jesus's story in the same way.
Syn- means "same" (as in synchronize, "same time"), and optic refers to sight. The first three Gospels are "syn-optic" because they see alike; they tell the story in similar ways, covering many of the same events. John, on the other hand, focuses on different material than the other authors, and has a high percentage of unique content.