Rain gutter, a narrow trough or duct which collects rainwater from the roof of a building and diverts it away from the structure, typically into a drain. A rain gutter is a narrow channel, or trough, forming the component of a roof system which collects and diverts rainwater shed by the roof The main purpose of a rain gutter is to protect a building's foundation by channeling water away from its base. The gutter also helps to reduce erosion prevents leaks in basements and crawlspaces, protects painted or stained surfaces by reducing exposure to water and provides a means to collect rainwater for later use. A rain gutter may be a: