Biotechnology is any technological application that uses biological systems, living organisms or derivatives thereof, to make or modify products or processes for specific use. Depending on the tools and applications, it often overlaps with the related fields of bioengineering,biomedical engineering, etc. For thousands of years, humankind has used biotechnology in agriculture, food production, and medicine.  In the late 20th and early 21st century, biotechnology has expanded to include new and diverse sciences such as genomics, recombinant gene techniques, applied immunology, and development ofpharmaceutical therapies and diagnostic tests. The wide concept of "biotech" or "biotechnology" encompasses a wide range of procedures for modifying living organisms according to human purposes, going back todomestication of animals, cultivation of plants, and "improvements" to these through breeding programs that employ artificial selection and hybridization. Modern usage also includes genetic engineering as well as cell and tissue culture technologies.