Mammals are warm-blooded vertebrates characterized by the presence of hair or fur, mammary glands for feeding their young, and typically give birth to live offspring. Articles are a unique way for readers to learn about the world around them. In addition to building reading comprehension skills and increasing vocabulary, articles can be used for writing and research. Animals are broken into 6 single-page sections: What Is, Characteristics, Types, Why Important, Fun Facts, and Words to Know.