see below Most patience or solitaire games involve building sequences of cards in suit in order in a family running from ace to king. Normally the ace is the base card or foundation on which a two of the same suit is placed, followed by a three and so on. This is building and all such games are, technically, builders. However, in many, the cards must be assembled in reverse order on that part of the layout called the tableau. They can then be built in the right sequence on the foundations. This intermediate step of reverse building is called packing, and games using this technique are called "packers". Games that use neither technique are "non-builders". There are also special kinds of packer known as 'blockades', 'planners' and 'spiders'. These games may be classified by the degree to which the cards are revealed. In "open games", all the cards are visible throughout the game and the player has to use powers of analysis to solve the patience. In "closed" games, cards are drawn from a face-down stock and the player has to use judgement because the sequence of cards is unknown until they appear. In between is a hybrid group which David Parlett calls "half-open". Closed games Closed games are those in which, throughout the game, not all the cards are visible. They require more judgment because the sequence of cards is unknown. As cards appear, if they cannot be played straight away they are put into a wastepile from which they may, potentially, not be accessible again. Closed games are subdivided as follows: Simple builders. Typically the aim of a simple builder is to build cards in suit sequence on the Aces which form the foundations. They are 'simple' in that the player has little or no choice in playing and just needs to watch for opportunities to build, any card that cannot be built being discarded to a wastepile where it may, of course, become inaccessible. Cards may be played from the wastepile or the hand and when the hand cards are exhausted it may be possible to 'redeal' by playing through the wastepile, usually for a limited number of times. Reserved builders. An elaboration of the simple builder is to deal a number of cards to a 'reserve', thus increasing the number of cards available to play. Simple packers. Packers enable cards to be built in reverse