Nearly one-fourth of the Earth's land is grassland. Grasslands have fewer than one tree per acre and have been described by New South Wales's Country Areas Program as "seas of grass." Grasslands generally get between 10 and 30 inches of rain per year. This is important because more rain than this would turn grasslands into forest. Conversely, grassland receiving less rain than this would become a desert.
A steppe is a particular type of grassland. Steppes are found on nearly every continent, with the exceptions of Australia and Antarctica. They are drier and colder than other grasslands. Steppes lack humidity because they are far from the ocean and near mountains. Mountains act as barriers, keeping moisture out. Few people live in the steppes as the soil quality is poor and, while there are numerous grasses, few other plants live there. Steppes are often an intermediate area between forests and deserts.
Savannas, sometimes called "tropical grasslands," generally lie between a tropical rainforest and a desert. As such, they are warmer than steppes. They get roughly the same amount of rain as a steppe, but most of it falls during the summer. Savannas get an average of between 15 and 25 inches of rain during this season. This balance is important because, like steppes, they can become either forests or deserts if the rain pattern shifts. Because they receive so much water, savannas support a few trees, but not enough to obscure the sky from beneath the way a nearby rainforest might. The plants and animals that do live here are highly specialized. They must withstand the long season of drought that follows the savanna's wet season.
There most important difference between a steppe and a savanna is where it is located. Savannas lie nearer the equator and are warmer than steppes. Being nearer the rainforest means they have two major seasons: a hot, wet summer and a marginally cooler, but much drier winter. Steppes, by contrast, lie further from the equator and in sheltered areas. This means the precipitation they get is dispersed evenly throughout the year. Fewer large plants can take root under such dry conditions. Being further from the equator also means colder conditions, and in some northern steppes, snow, rather than rain, is common.