Biology is the scientific study of life and living organisms.
It is a broad natural science that encompasses a wide range of fields and unifying principles that explain
the structure, function, growth, origin, evolution, and distribution of life. Central to biology are five fundamental themes: the cell as the basic unit of
life, genes and heredity as the basis of inheritance, evolution as the driver of biological diversity, energy transformation for sustaining life processes, and the
maintenance of internal stability (homeostasis).[1][2]
Biology examines life across multiple levels of organization, from molecules and cells to organisms, populations, and ecosystems. Subdisciplines
include molecular biology, physiology, ecology, evolutionary biology, developmental biology, and systematics, among others. Each of these fields applies a range
of methods to investigate biological phenomena, including observation, experimentation, and mathematical modeling. Modern biology is grounded in the theory of
evolution by natural selection, first articulated by Charles Darwin, and in the molecular understanding of genes encoded in DNA. The discovery of the structure of
DNA and advances in molecular genetics have transformed many areas of biology, leading to applications in medicine, agriculture, biotechnology,
and environmental science.
Life on Earth is believed to have originated over 3.7 billion years ago.[3] Today, it includes a vast diversity of organisms—from single-celled archaea and bacteria to
complex multicellular plants, fungi, and animals. Biologists classify organisms based on shared characteristics and evolutionary relationships,
using taxonomic and phylogenetic frameworks. These organisms interact with each other and with their environments in ecosystems, where they play roles
in energy flow and nutrient cycling. As a constantly evolving field, biology incorporates new discoveries and technologies that enhance the understanding of life
and its processes, while contributing to solutions for challenges such as disease, climate change, and biodiversity loss
