ANSWER: John (later referred to as "the Baptist" when he began to baptize people in the Jordan river) was born to a woman in her old age named Elizabeth. She had been barren but was healed by God (Luke 1:5 - 15, 36). She was a descendant of Israel's first high priest named Aaron (Luke 1:5) and a cousin of Jesus' mother Mary (Luke 1:36). Zacharias, the father, was a priest who served in Jerusalem's temple during Abia's course. This made John of priestly descent.
John the Baptist was set apart by God to be a Nazarite even before his conception (Luke 1:15). His miraculous birth, occurring just six months ahead of Jesus', took place in the late February to Early March time frame (at the same period of God's Feast Days known as Passover and Feast of Unleavened Bread) in 5 B.C. Not only was his arrival a miracle, it was also a fulfillment of prophecies which spoke of a voice in the wilderness (John 1:19 - 23) who would come in the spiritual power of Elijah (Matthew 17:10 - 13).
Nazarites were those who were consecrated to serve God and who were generally separated themselves from other people. John, as a Nazarite, was required to not drink any wine or strong drink, and could not even eat grapes or anything that had grapes in it. He also had to refrain from cutting his hair. Additionally, He could not come near or touch a dead body, even if it was his mother or father (Numbers 6:2 - 21).
John the Baptist spent the early part of his life dwelling in the rough, mountainous tract of land that existed between the city of Jerusalem and the Dead Sea (see Matthew 3:1 - 12). During most of his adult life he lived in the wilderness, away from the cities (Luke 1:80). His clothing was rough, and his diet was strict (Matthew 3:4, Mark 1:6).
God called John to prepare the people for Jesus' teaching and ministry. His ministry began when he was 30 years old (26 A.D.) and started to diminish when Christ's ministry began. He was put in prison by Herod Antipas for speaking out against his marriage to his sister-in-law Herodias. Christ stated the following about his unique ministry.
"What did you go out into the wilderness to see? A reed shaken by the wind? 8. But what did you go out to see? A man clothed in soft garments? Behold, those who wear soft clothing are in kings' houses. 9. But what did you go out to see? A prophet? Yes, I tell you, and one more excellent than a prophet. 10. For this is he of whom it is written, 'Behold, I send My messenger before Your face, who shall prepare Your way before You.' 11. Truly I say to you, there has not arisen among those born of women anyone greater than John the Baptist. But the one who is least in the kingdom of heaven is greater than he (Matthew 11:7 - 11, HBFV throughout)
Interestingly, even though Christ called John the greatest prophet, the Bible does not record him performing a single miracle (e.g. healing the sick, etc.). He was ultimately beheaded, during a celebration of Herod's birthday, in the Spring of 29 A.D. (just before the Passover).
Immediately after Jesus was transfigured, in the presence of three of his disciples, they asked Him about Elijah. They wanted to know why the scribes said he must appear before the end of the world. Jesus gave them the following answer.
10. Then His disciples asked Him, saying, "Why then do the scribes say that Elijah must come first?" 11. And Jesus answered and said to them, "Elijah shall indeed come first and restore all things. 12. But I tell you that Elijah has already come, and they did not recognize him; but they did to him whatever they desired. In like manner also, the Son of man is about to suffer from them." 13. Then the disciples understood that He was speaking to them about John the Baptist (Matthew 17:11 - 13).
God, in the very near future, will send not just one but two prophets to prepare the people for the second coming of Jesus Christ. You can read about them in the book of Revelation, chapter 11.