Aluminum and its alloys are today considered one of the most practical of metals for a variety of reasons. Its low cost,light-weight, and modern appearance are among the primary reasons for its widespread use. It is non-sparking, electrically conductive, thermally conductive, non-magnetic, reflective, and chemically resistant. It is popular in the construction, marine and aircraft industries because of its ease of fabrication, non-toxicity, strength (pound-for pound), and resistance to the corrosive atmospheres of industry and marine environments. Anodizing increases this corrosion resistance and also permits iridescent finishes in different colors. Some alloys are slightly corrosive and so are cladded with a thin layer of aluminum for added protection.