Many tux shirts—both the pleated and flat-front variety—come with smaller buttons and double buttonholes designed to accommodate shirt studs. To wear them, press the studs through the holes above the button, and use them to button your shirt. (It’s common to start at the second button, since the top button is typically covered by a bowtie.) The bar or backing will keep your shirt studs in place while you enjoy the party.
Because shirt studs are usually worn with evening wear, they are often styled with tuxedo jackets, vests, or cummerbunds. A set of three to five shirt studs is usually enough, depending on the shirt.