A waterfall is a natural feature where water cascades over a vertical drop or cliff. This phenomenon occurs in rivers when the water flows over harder rock layers that resist erosion, creating a sudden drop. Waterfalls can vary in size, from small trickles to massive torrents, and are often found in scenic locations, attracting visitors and nature enthusiasts. Waterfalls are formed through geological processes over time, including erosion and weathering. Famous examples include Niagara Falls, which straddles the border between Canada and the United States, and Angel Falls in Venezuela, known for being the highest waterfall in the world. These natural wonders play a crucial role in ecosystems and can create unique habitats for various species.