A non-conventional trademark, also known as a nontraditional trademark, is any new type of trademark which does not belong to a pre-existing, conventional category of trade mark, and which is often difficult to register, but which may nevertheless fulfill the essential trademark function of uniquely identifying the commercial origin of products or services. Non-conventional trademarks may therefore be visible signs (e.g. colors, shapes, moving images, holograms, positions), or non-visible signs (e.g. sounds, scents, tastes, textures).