Glass is an amorphous solid whose lack of long-range crystalline order gives it a distinctive combination of transparency, chemical stability, electrical insulation and brittle mechanical behavior.
Composition and structure
Silica is the main network former in many commercial glasses. Modifiers such as sodium and calcium oxides reduce melting temperature and adjust durability, while boron, aluminum and other additions tailor thermal and optical behavior.
Why glass is strong—and why it breaks
Ideal glass bonds are strong, but real surfaces contain flaws that concentrate tensile stress. Strength therefore depends heavily on surface condition, edge quality and flaw population rather than a single intrinsic number.
Strengthening methods
Thermal tempering introduces compressive surface stress. Chemical strengthening can exchange smaller ions for larger ones near the surface. Laminated glass uses polymer interlayers to improve post-breakage behavior.
Engineering applications
Glass is used in buildings, vehicles, optical fibers, displays, laboratory equipment, insulation and electronic substrates. Specialty glasses can be optimized for low thermal expansion, radiation resistance, chemical durability or optical transmission.