Rainwater harvesting is a technique for collecting and storing rainwater from various surfaces for reuse, offering benefits like groundwater recharge, irrigation, and reduced costs. It can be implemented through surface runoff or rooftop systems, with components including catchment areas, storage systems, and filtration methods for water purification. This practice promotes water conservation, provides a significant portion of domestic water needs, and has been made compulsory in several regions to combat water scarcity.