Ethology (from Greek: ἦθος, ethos, "character"; and -λογία, -logia, "the study of") is the scientific study of animal behavior, and a sub-topic of zoology.

Although many naturalists have studied aspects of animal behaviour throughout history, the modern discipline of ethology is generally considered to have begun during the 1930s with the work of Dutch biologist Nikolaas Tinbergen and Austrian biologists Konrad Lorenz and Karl von Frisch, joint winners of the 1973 Nobel Prize in Physiology or Medicine. Ethology is a combination of laboratory and field science, with a strong relation to certain other disciplines such as neuroanatomy, ecology, and evolution. Ethologists are typically interested in a behavioral process rather than in a particular animal group, and often study one type of behavior (e.g. aggression) in a number of unrelated animals.

The desire to understand animals has made ethology a rapidly growing field. Since the turn of the 21st century, many aspects of animal communication, animal emotions, animal culture, learning, and even sexual conduct that experts long thought they understood, have been reexamined, and new conclusions reached. New fields have developed, such as neuroethology.

Konrad Zacharias Lorenz FRS (November 7, 1903 in Vienna – February 27, 1989 in Vienna) was an Austrian zoologist, ethologist, and ornithologist. He shared the 1973 Nobel Prize with Nikolaas Tinbergen and Karl von Frisch. He is often regarded as one of the founders of modern ethology, developing an approach that began with an earlier generation, including his teacher Oskar Heinroth.

Lorenz studied instinctive behavior in animals, especially in greylag geese and jackdaws. Working with geese, he rediscovered the principle of imprinting (originally described by Douglas Spalding in the 19th century) in the behavior of nidifugous birds. In later life his interest shifted to the study of humans in society.

He wrote numerous books, some of which, such as King Solomon's Ring, On Aggression and Man Meets Dog became popular reading. His last work "Here I Am - Where Are You?" is a summary of his life's work and focuses on his famous studies of greylag geese.

In his autobiographical essay, published in 1973 in Les Prix Nobel (winners of the prizes are requested to provide such essays), Lorenz credits his career to his parents, who "were supremely tolerant of my inordinate love for animals," and to his childhood encounter with Selma Lagerlof's The Wonderful Adventures of Nils, which filled him with a great enthusiasm about wild geese.