Noah is a character in the Old Testament who was the focus of Chapters Genesis 6 through 9 in which God commanded him to build an arc for his family and two of every animal (male and female). This was because God was going to flood the earth and since Noah was among the most righteous of the people, he was chosen by God.
New Earth Christians hold that Noah was a real historical figure while Old Earth Christians hold that the flood and Noah's existence was merely a parable.