Metalloids are used very commonly in solid-state electronics, as components of alloys in metal objects, in glass and in flame- and heat-resistant objects. Metalloids in their pure forms are too brittle to be used in tools or in structural applications.
While metalloids alone are not strong enough for many applications, as alloys with metals they have many common uses. Many cars have parts made from alloys of the metalloid silicon and aluminum. Many people have decorations, jewelry, cups or flatware made from pewter, which is an alloy of the metalloid antimony and tin. Alloys of metalloids are commonly used in rewritable optical discs, such as compact discs, or CDs and digital video discs, or DVDs. These materials change from glassy to crystalline states with the application of heat, which makes them useful as data-storage media.
Compounds of silicon, such as silicone, are often used to reinforce plastics against flame and heat. Arsenic compounds can be used as flame retardants for wood, but their use is limited due to their toxicity. Many oxides of metalloids form glass, and many are used in making domestic glassware, although the most common is silicon dioxide. Metalloids are critical components of modern electronics, and the first transistors used them. Silicon is the leading semiconductor in these applications.