<P> The thickness and weight of modern playing cards is subject to numerous variables related to their purpose of use and associated material design for durability, stiffness, texture and appearance . </P> <P> Some decks include additional design elements . Casino blackjack decks may include markings intended for a machine to check the ranks of cards, or shifts in rank location to allow a manual check via inlaid mirror . Many casino decks and solitaire decks have four indices instead of just two . Many modern decks have bar code markings on the edge of the face to enable them to be sorted by machine (for playing duplicate bridge, especially simultaneous events where the same hands may be played at many different venues). Many decks have large indices, largely for use in stud poker games, where being able to read cards from a distance is a benefit and hand sizes are small . Some decks use four colors for the suits in order to make it easier to tell them apart: the most common set of colors is black (spades ♠), red (hearts ♥), blue (diamonds) and green (clubs ♣). Another common color set is borrowed from the German suits and uses green spades and yellow diamonds with red hearts and black clubs . </P> <P> When giving the full written name of a specific card, the rank is given first followed by the suit, e.g., "ace of spades". Shorthand notation may reflect this by listing the rank first, "A ♠"; this is common usage when discussing poker . Alternately, listing the suit first, as in "♠ K" for a single card or "♠ AKQ" for multiple cards, is common practice when writing about bridge; this helps differentiate between the card (s) and the contract (e.g. "4 ♥", a contract of four hearts). Tens may be either abbreviated to T or written as 10 . </P> <Table> Example set of 52 playing cards; 13 of each suit clubs, diamonds, hearts, and spades <Tr> <Th> </Th> <Th> Ace </Th> <Th> </Th> <Th> </Th> <Th> </Th> <Th> 5 </Th> <Th> 6 </Th> <Th> 7 </Th> <Th> 8 </Th> <Th> 9 </Th> <Th> 10 </Th> <Th> Jack </Th> <Th> Queen </Th> <Th> King </Th> </Tr> <Tr> <Th> Clubs </Th> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Th> Diamonds </Th> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Th> Hearts </Th> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Th> Spades </Th> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> </Table>

How many kinds in a deck of cards