Biology

Biology is the science of life. It is concerned with the physical characteristics and behaviors of organisms alive today and long ago, how they come into being, and what interactions they have with each other and their environments.
The word biology in its modern sense seems to have been introduced independently by Gottfried Reinhold Treviranus (Biologie oder Philosophie der lebenden Natur, 1802) and by Jean-Baptiste Lamarck (Hydrogéologie, 1802). The word itself is sometimes said to have been coined in 1800 by Karl Friedrich Burdach, but it appears in the title of Volume 3 of Michael Christoph Hanov's Philosophiae naturalis sive physicae dogmaticae: Geologia, biologia, phytologia generalis et dendrologia, published in 1766. Today the term encompasses a broad spectrum of academic fields that are often viewed as independent disciplines.

Overview of biology
Biologists study life over a wide range of scales:

at the atomic and molecular scale, through molecular biology, biochemistry
at the cellular scale, through cell biology
at the multicellular scales, through physiology
at the level of the development or ontogeny of an individual organism, through developmental biology
at the level of heredity between parent and offspring through genetics
at the level of group behavior through ethology
at the level of an entire population, through population genetics
on the multi-species scale of lineages, through systematics
at the level of interdependent populations and their habitats through ecology and evolutionary biology
and speculatively through Xenobiology at the level of life beyond the Earth.

Fields of study in biology
Aerobiology -- Anatomy -- Astrobiology -- Biochemistry -- Bionics -- Biogeography -- Bioinformatics -- Biophysics-- Biotechnology -- Botany -- Cell biology -- Cladistics -- Cryptozoology -- Developmental biology -- Disease (Genetic diseases) -- Ecology (Theoretical ecology, Autecology, Synecology) -- Ethology -- Genetics (Population genetics, Quantitative genetics, Genomics, Proteomics) -- Ichthyology -- Immunology -- Pathology -- Epidemiology -- Limnology -- Malacology -- Marine biology -- Microbiology (Bacteriology) -- Molecular Biology -- Mycology / Lichenology --- Neuroscience (Neuroanatomy, Biological psychology, Psychiatry, Psychopharmacology, Behavioral science, Computational neuroscience, Cognitive science)-- Oncology (the study of cancer) -- Ontogeny -- Paleontology -- Phycology (Algology) -- Phylogeny, Phylogeography) -- Physiology -- Structural biology -- Taxonomy -- Toxicology (the study of poisons and pollution) -- Xenobiology -- Zoology

Related disciplines
Physical anthropology

People and history
History of biology -- Nobel prize in physiology or medicine -- Timeline of biology and organic chemistry

Evolution and biology
One of the central, organizing concepts in biology is that all life has descended from a common origin through a process of evolution. Charles Darwin articulated the concept of evolution that remains central to this day, which he did by proposing natural selection as a mechanism. Genetic drift was embraced as an additional mechanism in the so-called modern synthesis. The evolutionary history of a species--which tells the characteristics of the species from which it descended--and its relationship to other species is called its phylogeny. Widely varied approaches to biology generate information about phylogeny. These include the comparisons of DNA sequences conducted within molecular biology or genomics, and comparisons of fossils or other records of ancient organisms in paleontology. Biologists organize and analyze evolutionary relationships through various methods, including phylogenetics, phenetics, and cladistics

Classification of life
The classification of living things is called systematics, or taxonomy, and should reflect the evolutionary trees (phylogenetic trees) of the different organisms. Taxonomy piles up organisms in groups called taxa, while systematics seeks their relationships. The dominant system is called Linnaean taxonomy, which includes ranks and binomial nomenclature. How organisms are named is governed by international agreements such as the International Code of Botanical Nomenclature (ICBN), the International Code of Zoological Nomenclature (ICZN), and the International Code of Nomenclature of Bacteria (ICNB). A fourth Draft BioCode was published in 1997 in an attempt to standardize naming in the three areas, but it does not appear to have yet been formally adopted. The International Code of Virus Classification and Nomenclature (ICVCN) remains outside the BioCode.
Traditionally, living things were divided into five kingdoms:

Monera -- Protista -- Fungi -- Plantae -- Animalia
However, this five-kingdom system is now considered by many to be outdated. More modern alternatives generally begin with the three-domain system:

Archaea -- Eubacteria -- Eukaryota
These domains reflect whether cells have nuclei or not as well as differences in cell exteriors.
There is also a series of intracellular "parasites" that are progressively less alive in terms of being metabolically active:

Viruses -- Viroids -- Prions