The Gospels don't explicitly say whether John the Baptist and Jesus had met before the baptism, but they do offer some clues that suggest they likely had not. Here's a breakdown of the evidence:
* John's initial testimony: In the Gospel of John (1:31-33), John the Baptist says, "I myself did not know him, but the reason I came baptizing with water was that he might be revealed to Israel...I did not know him, but the one who sent me to baptize with water told me, 'The man on whom you see the Spirit come down and remain is the one who will baptize with the Holy Spirit.'" This implies that John wasn't personally acquainted with Jesus before the Spirit descended on him at the baptism.
* Matthew's account of John's hesitancy: In Matthew 3:14, John tries to deter Jesus, saying, "I need to be baptized by you, and do you come to me?" This could be interpreted as John not fully grasping Jesus's identity until that moment.
While the Gospels suggest they hadn't met before, it's also possible that they had a brief encounter or knew of each other through family connections (they were relatives). However, the emphasis in the biblical accounts is on the revelation of Jesus's identity *at* the baptism, suggesting it was a significant, revelatory event for John as well.