Annas and Caiaphas were Jewish high priests. Annas served from AD 6 to 15 until the Romans removed him. His son-in-law, Caiaphas, was the high priest from AD 18 to 36. Luke mentions both names because Annas was still very influential among the Jews (see John 18:13–14, 24; Acts 4:6).
the word of God came to John son of Zechariah: John's role as a prophet was similar to that of the Old Testament prophets (see, for example, Isaiah 6; Jeremiah 1).