Botany is the study of plants. It is a science. It is a branch of biology.
It is also called plant biology, and sometimes phytology. Scientists who study botany are called botanists. They study how plants work.
University departments of botany are often now merged into a wider group of specialities, including cell biology, genetics, ecology, cytology, palaeontology and other topics. This gives students and research workers access to a wider education and a wider range of research techniques.