The difference between “domesticated animal” and “domestic animal” lies in how these terms describe the relationship between animals and humans. This work aimed to determine the best way to employ these denominations. The etymology of the word “domestication” is Latin (domus) and means “house” or “home.” It refers to the process by which an animal population adapts to humans through genetic changes that occur over generations, being environmentally induced in each generation. Domestication derives from the separation of a species from its natural ecological context, its development under artificial selection pressure in artificial environments, and may involve behavioral, physical, and genetic changes that allow living and reproducing in coexistence with humans. It is a result of cultural aspects and human intellectual capacity. “Domesticated animals” have undergone the domestication process for generations, displaying specific characteristics such as traits desirable for reproduction and coexistence, generally in controlled environments. Examples of “domesticated animals” include dogs, domesticated approximately 15,000 to 40,000 years ago, with friendly behaviors and functional abilities such as hunting and guarding; and cattle, domesticated approximately 10,000 years ago, selected for characteristics such as size, docility, and capacity to produce milk and meat. “Domestic animals” live with humans in domestic environments (houses or apartments), being considered pets (companion or pet animals), integrated into the family, residential, and daily environment of people. Not all “domestic animals” are results of domestication processes. Some of them may be exotic (do not belong to the national fauna) or wild (belong to the national fauna) and be kept in domestic environments. Examples of “domestic animals” include parrots, which, despite being domesticated, still maintain many wild behaviors; rabbits, which can be pets and live in houses, but their domestication is limited compared to dogs and cats, and may exhibit atavistic behaviors such as digging and gnawing. Most pets are both domestic and domesticated. Less common or exotic pets may be only domestic, with varying levels of domestication. A “domesticated animal” has undergone an adaptation process to life with humans. On the other side, the condition of being a ” domestic animal” is about the presence and effective coexistence in a residential environment.