An O'Neill Cylinder is a proposed space habitat designed by physicist Gerard K. O'Neill in the 1970s. It consists of two counter-rotating cylinders that create artificial gravity through centrifugal force. The interior of the cylinders would be designed to support human life, featuring landscapes, agriculture, and living spaces. These habitats could accommodate thousands of people and provide a sustainable environment for long-term space living. The concept aims to utilize resources from space, such as asteroids and the Moon, to support human activities beyond Earth, promoting the idea of expanding human civilization into the cosmos.