Tuck box
A tuck box is a small folded cardboard box with a tucked flap (instead of a glued top) that holds a deck of cards. It's the standard packaging for a single-deck game and the cheapest way to ship a card-only product.
Why it matters
You design a tuck box once your deck is ready to sell or print as a complete product. Print-on-demand services supply the dieline; you wrap your art around it.
Example
A 54-card poker deck typically fits a tuck box around 2.6" × 3.6" × 0.85". The flat dieline gives you five visible panels — front, back, two sides, top — to design.