Animal testing, also known as animal experimentation, involves using non-human animals for experiments. It is estimated that 50-100 million vertebrate animals are used annually worldwide for research and testing. Animals are used in universities, medical schools, pharmaceutical companies, and other facilities for various types of research including basic science, biomedical research, drug testing, toxicology tests, and education. Supporters argue that animal research has contributed to many medical advances, while critics question its ethics and scientific validity. Regulations aim to balance the research needs with ensuring humane treatment of laboratory animals.