A savanna is a large, grassy plain with scattered trees, found in warm regions where there's a long dry season each year. Picture a golden grassland stretching to the horizon, dotted with flat-topped acacia trees and home to grazing animals like zebras, elephants, and giraffes. That's the classic African savanna, though savannas also exist in South America, Australia, and India.

What makes savannas unique is their balance between grassland and forest. They get enough rain to support grass and some trees, but not enough for a thick forest to grow. During the wet season, the grass grows tall and lush. During the dry season, much of it turns brown and brittle, and wildfires often sweep across the landscape. These fires actually help the savanna thrive: grasses have deep roots that survive underground, while many tree seedlings can't take the heat, keeping the landscape open.

Savannas cover about 20 percent of Earth's land surface and support an incredible diversity of wildlife that has adapted to the cycles of rain, drought, and fire.