The suit symbols on playing cards have an origin not widely known to many. Playing cards today use French suit symbols, though it was not always this way. When playing cards entered Europe around the mid 1300s the suit system then were Swords, Rods, Coins, and Cups. Scholars believe these suits represented the four classes of people during this time period. These classes were the soldiers, farmers, merchants, and clergy. The Italian duplicated this system and it spread throughout Europe even more. The Italian altered the suits to match their classes. They used Coins, Swords, Cups, and Batons.
The suits began to vary as the cards spread even further; for example, the Germans produced suits similar to modern day ones. Their version consisted of Hearts, Bells, Leaves, and Acorns. The Hearts and Bells were red while the Leaves and Acorns were green. Like the original European suits, these also represented the classes of people during the time. In the German system Hearts stood for the church, Bells for the nobles, Leaves for the middle class, and Acorns represented the peasants. These set of suits were mainly used in Eastern Germany, while in the West they used the French deck most of the time.
In the 15th century cards started to spread to France as well. From there the modern day suit system was born which are the Hearts, Diamonds, Clovers, and Spades. The Hearts represent the church, Diamonds symbolized the archers, Clovers represented the shepherds, and Spades expressed the knights. This explains why Spades are ranked of highest value as opposed to Clover which ranks the lowest, though this can also depend on the type of game being played. In games such as Bridge the rank of the suits are important, but in games like Blackjack the suits are ignored entirely.