The cactus is a type of plant that belongs to the family Cactaceae. It is well-known for its ability to thrive in arid environments, thanks to its thick, fleshy stems that store water. Cacti often have spines instead of leaves, which help reduce water loss and protect them from herbivores. There are over 2,000 species of cacti, varying in size and shape. Some common types include the Saguaro, which can grow tall and live for over 150 years, and the Barrel cactus, known for its round shape. Cacti are also popular as houseplants due to their low maintenance needs.