According to Genesis, Noah built the ark before the Flood.
In the biblical account, God warns Noah that a catastrophic flood is coming because of widespread human wickedness. Noah is instructed to construct a large vessel, bring aboard his family, and preserve pairs of land animals and birds. Genesis presents Noah as righteous among the people of his time and as the central human figure in the Flood story.
The name Noah comes from the Hebrew נֹחַ (Noaḥ). The story appears in Genesis chapters 6–9, while related flood traditions occur in the Quran and in much older Mesopotamian literature, including the Epic of Gilgamesh. Those accounts use different character names and details.
A common mix-up is crediting the ark’s construction to one of Noah’s sons. Genesis names Shem, Ham, and Japheth as Noah’s sons, but Noah himself receives the building instructions and carries them out.