The main account of Noah in the Bible is in the book of Genesis.
This represents very ancient, distant and dim times, even for the people who wrote up the story of Noah. Essentially the story goes like this: There had been trouble and the Lord was displeased. As a result, He was going to 'wipe the slate clean and start again'. He was going to do this by flooding the world. However, "Noah found grace in the eyes of the Lord." (Genesis 6:1-8)
Noah was instructed by God to "make an ark", and fill it with two of every sort of living thing, and gather "all food that is eaten" for provisions for them all. (Genesis 6:11-22)
After the Flood, Noah offered burnt offerings to the Lord, who said: "I will not again curse the ground any more for man's sake...neither will I again smite any more every thing living, as I have done." (Genesis 8:20-21)
"And God blessed Noah and his sons, and said unto them, Be fruitful, and multiply, and replenish the earth." (Genesis 9:1)
At the same time, God told Noah that everything in the world was to be food for man except that the blood of man was not to be eaten. And "Whoso sheddeth man's blood, by man shall his blood be shed: for in the image of God made he man." (Genesis 9:6)
Noah is supposed to have died 350 years after the Flood, at the age of 950.
Most people who study the Bible agree that this is a way of telling people some basic truths. The numbers are just there to mean 'he lived a long time until he was very old'. The flood may also be a story designed to give an example of how God could become angry against those who did not do His will.
For many thousands of years people believed that the Flood was real and they explained everything in terms of it. Since the discovery of fossils and the development of the ideas of evolution, most people have chosen to see Noah's story as a way of giving over an important message in a way that could be understood by everyone, not meant to be taken literally.
What about the flood itself? This could appear real enough, for in the Middle East, rivers like the Euphrates do flood, and when they do, the waters reach as far as the eye can see, which in older times might well have been seen as the whole world. So making up a story using a flood would have seemed real enough to the people who lived in the area at the time.
