The minimum Deck size is the lower limit on the number of cards allowed in a player's Main, Extra, and Side Decks, and is a counterpart to the maximum Deck size. This limit has always been 40 cards for the Main Deck; the Extra and Side Decks have always been allowed to have zero cards (though before the maximum Deck size was introduced, a player's Side Deck was required to contain either exactly zero or exactly 15 cards).