system
Given the following post, respond as if you're commenting on Reddit:
human
Why does glass appear transparent?

It's made from solid matter and even when very thick appears clear. What's the transparent property? And do other animals also see it as transparent?
gpt
Glass is transparent to visible light. Matter will be opaque when it is made up of atoms or molecules that scatter light or absorb light. Rough glass will scatter light, this is why sand isn't transparent. Glass used in windows or other things is made smooth by letting it cool from a molten state. 

And glass simply doesn't absorb visible light. The electrons in a glass molecule are bound too tightly to be excited by visible light.