Most of us are familiar with the tale of Noah and the flood. For those of you who aren't, here's a quick recap.
God is mad at humanity and decides to wipe us all out by flooding the earth. The only person God doesn't seem to hate is Noah, so He warns Noah of the impending flood. God orders Noah to build an ark, providing specific instructions about the dimensions and materials to be used. In the ark, Noah is to gather his family and two of every animal.
Noah does as he is told. He builds the ark, gathers his family and marches all the animals on board two by two. Then, it starts to rain.
God makes it rain for 40 days and 40 nights, flooding the earth. Noah, his family and the animals he gathered are the only survivors.
After the rains had stopped, Noah released a raven, which never returned. Seven days later, Noah released a dove, which returned having found nothing to land on. Seven days after that, Noah released the dove again. This time it returned with a sprig of olive. Another seven days and Noah released the dove. It never returned. Another seven days and Noah released the dove one last time. It never returned.
Noah knew this meant the dove had found land. The waters subsided and the ark landed on a mountain. Noah, his family and the animals left the ark, and God promised never to flood the earth again. And he left us the rainbow as a sign of this covenant.