Card stock is basically a paper with thickness somewhere in between a normal printing paper and a paper board. It is also known as cover stock. Cardstocks are thicker and last longer than printing paper. It is more flexible to use and mainly used to make  business cards, post cards, etc. It is available in different colors, thickness, and texture.  Often business people get their logo/design on cards with the help of artists and graphic designers. The term is also used to denote a stored supply of covers or cards.