Ethology is the scientific study of animal behaviour, usually with a focus on behaviour under natural conditions, and viewing behaviour as an evolutionarily adaptive trait. Behaviourism as a term also describes the scientific and objective study of animal behaviour, usually referring to measured responses to stimuli or to trained behavioural responses in a laboratory context, without a particular emphasis on evolutionary adaptivity. Throughout history, different naturalists have studied aspects of animal behaviour. Ethology has its scientific roots in the work of Charles Darwin (1809–1882) and of American and German ornithologists of the late 19th and early 20th century, including Charles O. Whitman, Oskar Heinroth (1871–1945), and Wallace Craig. The modern discipline of ethology is generally considered to have begun during the 1930s with the work of Dutch biologist Nikolaas Tinbergen (1907–1988) and of Austrian biologists Konrad Lorenz and Karl von Frisch (1886–1982), the three recipients of the 1973 Nobel Prize in Physiology or Medicine. Ethology combines laboratory and field science, with a strong relation to some other disciplines such as neuroanatomy, ecology, and evolutionary biology. Ethnologists typically show interest in a behavioural process rather than in a particular animal group, and often study one type of behaviour, such as aggression, in a number of unrelated species.

Ethology is a rapidly growing field. Since the dawn of the 21st century researchers have re-examined and reached new conclusions in many aspects of animal communication, emotions, culture, learning and sexuality that the scientific community long thought it understood. New fields, such as neuroethology, have developed.

Understanding ethology or animal behaviour can be important in animal training. Considering the natural behaviours of different species or breeds enables trainers to select the individuals best suited to perform the required task. It also enables trainers to encourage the performance of naturally occurring behaviours and the discontinuance of undesirable behaviours.

A research project in animal behaviour will of course always contain elements from almost all the fields treated in this report. Initially the animals under study have to be marked and identified, and a selection of the most appropriate sampling methods must be made. The behaviour patterns of interest will have to be described and named. Certain behavior patterns will probably be measured by frequency analysis, some with continuous counting’s and some with instantaneous sampling. Other behavior patterns will perhaps be studied through sequence analysis. At the end, differences between groups or individuals must be tested for statistical significance. It is therefore necessary that everyone involved in behaviour studies is familiar with the possibilities and limitations of the prevailing methods for sampling and analysis.