Ethidium bromide, also sometimes referred to as ethobromide, homidium bromide, and dromilac, appears as dark red crystals when it is pure and dry. When utilized in the laboratory, however, and examined under either long or short ultraviolet (UV) wavelengths of light, a reddish-orange fluorescence can be easily detected. A relatively large, flat molecule, ethidium bromide appears somewhat similar to a DNA base pair and can easily insert into strands of the material due to its chemical structure. Thus, when bound to double-stranded DNA molecules, increased fluorescence of ethidium bromide occurs.