Definition of carpet
A poker tournament stack is the total amount of chips a player has. In English, we speak of his stack, a word that is often used even by French speakers. In cash games, the stack is the total amount of big blinds a player has. If he bought in for 100 big blinds and won a few pots to bring his total blinds up to 180 big blinds, or say 360 big blinds in a case where the big blinds were 2 big blinds, this amount would be identified as his stack.
The carpet, a powerful tool for the poker player
A rug is not just abstract information about a player. An all-in is also a tool that you can use to your advantage, to bluff or take certain risks. For example, if you have 180 big blinds in your stack and a player before you has only 10 big blinds that he pushes all in, since his stack is small, to go to the showdown, you know it will only cost you 10 big blinds. And if the player had 180 big blinds as well, you would know going into the hand that you would be risking your entire stack.