ISAIAH was born around the year 700 BC. Remember that 'BC' means before Christ. He lived in Jerusalem and he had a vision in which he saw the Lord sitting upon a throne. And he heard the voice of the Lord saying, "Whom shall I send and who will go for us?" Isaiah answered the Lord, "Here am I, Send me!"
And so Isaiah traveled all over and told people to prepare and be ready for the coming Messiah. This is why during Advent the readings are from the book of Isaiah in which he speaks of being prepared.
JOHN THE BAPTIST was the son of Zachary and Elizabeth. Zachary saw an angel who told him that his wife Elizabeth would have a son and that they should call him John. Also, that John would help Israel prepare for the Messiah. Zachary was confused and doubted that his wife Elizabeth would have a baby as they were very, very old. But it did happen! Elizabeth gave birth to a son whom they named John. John was born 6 months before Jesus.
Elizabeth is a cousin of Mary, the Mother of God. When Mary visited Elizabeth before John was born, the baby moved inside of her. Elizabeth recognized then that her son John had a special mission ahead of him.
In the Gospel of Luke, Chapter 1, Verses 41 and 42 say:
When Elizabeth heard Mary’s greeting, the infant leaped in her womb, and Elizabeth, filled with the holy Spirit,
cried out in a loud voice and said, “Most blessed are you among women, and blessed is the fruit of your womb.
This should be very familiar as it is from the HAIL MARY prayer, too.