A vivarium is an area, usually enclosed, for keeping and raising animals or plants for observation or research. Water-based vivaria may have open tops providing they are not connected to other water bodies. An animal enclosure is considered a vivarium only if it provides quality of life through naturalistic components such as ample living space and natural decor that allow and encourage natural behaviours. Often, a portion of the ecosystem for a particular species is simulated on a smaller scale, with controls for environmental conditions such as temperature, humidity and light.

A terrarium is usually a sealable glass container containing soil and plants that can be opened for maintenance to access the plants inside; however, terraria can also be open to the atmosphere. Terraria are often kept as ornamental items.