For most people, "button-down" and "button-up" are interchangeable, but they're actually not the same item of clothing.

but the button-down collar shirt actually traces its history to the sport of polo. As the story goes, in 1896, John Brooks, ...

was inspired by English polo players. Oxford button-down shirts typically feature a durable basketweave fabric and classic button detailing up to the collar. The dress shirt is an essential ...