Animals are multicellular, eukaryotic organisms that belong to the kingdom Animalia. They are characterized by their ability to move voluntarily, usually with the presence of specialized sensory organs, such as eyes, ears, and noses. Animals come in a wide variety of shapes, sizes, and behaviors, ranging from microscopic organisms like the tardigrade to the massive blue whale. They can be found in nearly every habitat on Earth, from the depths of the ocean to the highest mountaintops. Animals play vital roles in ecosystems as predators, prey, pollinators, scavengers, and more. They exhibit diverse feeding strategies, reproductive methods, and social structures, making them a fascinating subject of study for biologists and zoologists worldwide.