The document discusses different types of plains, including coastal plains which are flat, low-lying landforms near oceans or large lakes that are home to natural resources. It also describes the Northern Fertile Plain/Gangetic Plain of India, which is one of the largest and most fertile plains in the world, densely populated and an important agricultural region. The Great Plains of North America are also mentioned as a broad expanse of flat land covered in prairie and grasslands west of the Mississippi River and east of the Rocky Mountains.