The classic white button-down.

In crisp cotton or soft silk, the tailored shape of the shirt brings elegance to distressed denim or conservative suiting. Smart women rely on this true wear-anywhere closet staple for the office, a night out or a weekend stroll. Tuck it in or let it hang loose, you can’t go wrong with a white shirt. Throw it over a tee and worn jeans, tuck it into a black pencil skirt or top it with a tweed blazer.  Glamour.com shows eighteen photos.