Metazoans are a diverse group of multicellular organisms that include animals like humans, fish, and insects. They are characterized by their complex structures and specialized cells that work together to perform various functions. Metazoans can be found in many environments, from deep oceans to lush forests, showcasing a wide range of shapes, sizes, and behaviors. These organisms are classified into different groups based on their characteristics, such as vertebrates and invertebrates. Metazoans play crucial roles in ecosystems, contributing to food webs and nutrient cycles. Their evolutionary history dates back over 600 million years, making them an essential part of life on Earth.