Who was John the Baptist?:
John the Baptist (also: John the Baptizer) appears in each of the four gospels as a figure preaching the immediate coming of a Messiah. John is depicted in a manner consistent with Jewish eschatological expectations: dressed and acting like Elijah, John is preparing the way for the Messiah as well as the last days. Gospel stories suggest that Johns ministry was popular and successful. According to Luke, he was born into a priestly family.
When did John the Baptist live?:
John the Baptist lived during the first half of the first century. When he was born and how old he was when he died are unknown. Lukes account of Johns birth, claiming that his parents were the priest Zechariah and his wife Elizabeth, suggests that he would have been the same age as Jesus.
Where did John the Baptist live?:
John the Baptist would have been active primarily in Galilee, around the Jordan River. Although the Jordan was not suitable for the purposes of agriculture or navigation, there are a couple of locations that seem to have been used for baptisms.
What did John the Baptist do?:
Today baptism is associated with Jesus, but nowhere in the gospels is he shown baptizing anyone. John the Baptist, however, is depicted as participating in what might have been a very popular activity. According to gospel accounts, he preached that simply being descended from Abraham wasnt enough for salvation; only repentance and a renunciation of any privileges based upon lineage or election would suffice.
Did John the Baptist exist?:
The existence of John the Baptist is disputed. The only extra-biblical mention of him is found in Josephus Antiquities and is arguably an interpolation a later addition by someone else which tells a different story from the one in the gospels. If Josephus is accurate, then the gospels are not; if Josephus is not accurate, then the basis for thinking that John the Baptist existed (and hence that the gospels are accurate) is undermined.
Why was John the Baptist important?:
Some scholars suspect that Jesus could have been a follower of John the Baptist who went off on his own to create a new religious movement. If this were the case, then its only natural that Jesus followers would need to make theirs appear to be the more important of the two groups. There definitely appears to be such a concern in the gospels: Mark makes John the Baptist still seem important, Matthew has John the Baptist acknowledge Jesus superiority, and Luke ends up excluding John the Baptist completely. Each succeeding text pushes John further and further into the background.