John called people to repent and baptized them in the Jordan River.

John was born to an elderly couple - Zechariah a priest and Elizabeth his wife, a kinswoman of Mary the mother of Jesus. He later lived in the wilderness of Judea. He wore camel's hair and a leather girdle, which was similar to the garb worn by Elijah. John baptized many with water, pointing to Jesus the Messiah as the one who would baptize with fire. When Herod Antipas married his sister-in-law Herodias, John condemned the action. Herod arrested John.  While in prison, John sent messengers to ascertain Jesus' identity and was told of Jesus' miracles.  Later Herod beheaded John.

Mark 1:1-8 - John's preaching
Mark 1:9-11 - John baptizes Jesus
Luke 7:18-23 - John asks about Jesus' identity
Mark 6:14-29 - John's death