Why are spades and clubs black while hearts and diamonds are red?

The standard international deck, which features two black suits (spades and clubs) and two red suits (hearts and diamonds), evolved from French designs created around 1490.12

These suitmarks—technically designated as French—were developed as a simplified design using stencils to reduce production costs. While earlier European decks featured various regional suit systems, the French design became the international standard due to its popularity and ease of manufacture. The specific color-coding of these suits is a characteristic feature of this French-originated system, which replaced more complex, hand-painted designs that were previously luxury goods for the wealthy.23

The names of the suits themselves reflect historical influences: spade likely derives from the Old Spanish spado (sword), and club is a translation of the Spanish basto, suggesting that Spanish suit traditions influenced English card terminology before the French design became dominant.1