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.

The Wardian case was an early type of terrarium, a sealed protective container for plants. It found great use in the 19th century in protecting foreign plants imported to Europe from overseas, the great majority of which had previously died from exposure during long sea journeys, frustrating the many scientific and amateur botanists of the time. The Wardian case was the direct forerunner of the modern terrarium and vivarium and the inspiration for the glass aquarium. It is named after Nathaniel Bagshaw Ward (1791–1868) of London, who promoted the case after experiments.