A cactus is a type of plant that belongs to the family Cactaceae. These plants are well-known for their ability to thrive in dry, arid environments, such as deserts. Cacti have thick, fleshy stems that store water, allowing them to survive long periods without rainfall. Many cacti also have spines instead of leaves, which help reduce water loss and protect them from herbivores. Cacti come in various shapes and sizes, ranging from small, round varieties to tall, tree-like forms. Some popular types include the Saguaro cactus, which can grow to be quite large, and the Barrel cactus, known for its rounded shape. Cacti are also often used in gardens and landscaping due to their unique appearance and low maintenance needs.