"Miniature Art" refers to a very specific, specialized fine art form.  The pieces are typically less than 25 square inches in size, and are created with very fine brush strokes, under magnification.  This allows the art to be magnified - even projected onto a movie screen - and still it holds up as a fine art painting.  Miniature art dates back to the 17th century, when portrait artists would create pieces that loved ones would keep in their pockets and treasure always.  This is a very exacting, intimate type of art and modern miniature guidelines restrict the type of frames to be used, insist on a high level of detail, and a 1/6 or smaller scale.  This means that a human head, typically 9", can be depicted no larger than 1.5" in a miniature painting.  You can imagine the skill and patience it takes to create fine art that meets these requirements.