Today is the International Day for Biosphere Reserves. Biosphere reserves may sound like a mouthful, but they're essentially nature's sweet spots— biodiverse places that are home to a huge variety of life. These reserves, recognized by UNESCO, keep ecosystems healthy, protect endangered species, and help regulate climate through forests, wetlands, and other crucial habitats. There are 759 biosphere reserves across 136 countries. From the lush greenery of the Sundarbans in India to the vast expanses of the Great Sandy Biosphere Reserve in Australia, each reserve is unique.