Many sub-disciplines and special areas of biology exist, which can be conveniently divided into practical and theoretical categories. Types of practical biology include plant breeding, wildlife management, medical science, and crop production. Theoretical biology encompasses such disciplines as physiology (the study of the function of living things), biochemistry (the study of the chemistry of organisms), taxonomy (classification), ecology (the study of populations and their environments), and microbiology (the study of microscopic organisms).
Biology is one of the major sciences. Scientists have acquired biological knowledge through processes known as scientific methods. There is no one scientific method. The steps of a scientific method make up an orderly way of gaining information about the biological world. The knowledge gained is sometimes useful in solving particular problems, and is sometimes simply of interest, without any practical application at the time.