Without the Torah, mankind's moral standards declined so sharply that the majority of people became filled with hatred for each other. They commonly practiced violent robbery, sexual immorality and all forms of perverse idolatry.
In the tenth generation from Adam, God regretted ever having created mankind, and resolved to destroy the world and start anew.
There was, however, one man who had preserved the Torah and remained faithful to its teachings. Because of this, he alone was worthy to be spared. This man was called Noach ("Noah"). He was a man of great wisdom and a prophet. His wife and three sons shared his high level of conduct.
God spoke to Noach, and told him of His intent to destroy the world through a flood. He then instructed Noach to build a large boat in view of the people of his generation over a long period of time, in the hope that by watching his efforts they would come to regret their actions and would change their ways. But, it was not so, and they all perished in the flood.
The only survivors were Noach and his family, and a remnant of every species of animal that had not been corrupted by the people of their generation.
When Noach and his family emerged from the boat, the Creator reiterated the Torah that he had previously given to Adam, with the addition of an injunction prohibiting cruelty to animals.
This code of conduct is known to this day as the "Seven Laws of Noach."