I'm a big fan of breezy white curtains, but sometimes a bolder choice is in order. Opting for black can add contrast, which is always refreshing, and brings a little moodiness.
Black curtains are a less expected way to dress your windows, but they work in grand bedrooms (Image 4), earthy, organic settings (Image 3), and modern living spaces (Image 1). They add contrast to white walls and visual consistency to dark rooms. They can also help to highlight tall ceilings (flaunt 'em if you got 'em).
(Images: 1. Isabel & Claire's Globetrotting Apartment 2. A Look Inside the Home of Lighting Designer Marjorie Skouras 3. Noma restaurant via Business Insider 4. Kravitz Design 5. Taverne Agency via Greetings From Holland)