To block obscure lights
To block drafts
To block water, in the case of a shower curtain
Stopping people outside from being able to see inside, often for privacy reasons
Stopping people inside from being able to see outside, often for no reason
Comes in a variety of shapes, materials, sizes, colors and patterns
In the US also known as a drape
In the UK also known as drapery.
Curtain, a piece of cloth, in 12 photographs.