What is glass made of?

Glass is an amorphous, non-crystalline form of silica (silIcon dioxide). In it’s crystal form it’s called quartz.

Fun Fact: Glass, although a solid, is also a fluid. Fluid doesn’t mean liquid, but rather anything able to flow. that’s why old glass is thicker at the bottom and gives that great distortion to light passing though it. It is actually flowing downward under gravity at an incredibly slow rate.