What the starting layout looks like
Pyramid uses one standard deck of 52 cards. A pyramid of 28 cards is built in seven rows: one card in the top row, two in the second, then three, and so on down to seven cards in the bottom row. The remaining cards go to the stock and are later turned over one at a time into the waste.
Only pyramid cards that are not covered by two cards from the row below count as available. If a card is still "holding up the roof", it cannot be removed. So the whole game is about clearing the lower levels and gradually opening up more and more available cards.