Art glass is a subset of glass art, this latter covering the whole range of art made from glass. Art glass normally refers only to pieces made since the mid-19th century, and typically to those purely made as sculpture or decorative art, with no main utilitarian function, such as serving as a drinking vessel, though of course stained glass keeps the weather out, and bowls may still be useful.
The term is most used of American glass, where the style is "the logical outcome of the American demand for novelty during the 19th century and was characterized by elaborate form and exotic finish", but not always the highest quality of execution. There was a great interest in complex colour effects and painted enamelled glass. For art historians the "art glass" phase replaced the "Brilliant Period" of High-Victorian heavy decoration, and was in turn was replaced around 1900 by Art Nouveau glass, but the term may still be used for marketing purposes to refer to contemporary products. In fact the "Brilliant Period" style, which relied on deeply cut glass, continued to be made until about 1915, and sometimes thereafter.