Color (色 Iro) is a parameter possessed by a card. A card may have one of the five possible color:
In addition, there is also exist colorless cards, which are represented with a grey circle (known as "None") or sometimes, generic Ignition Icon. Set 16 also introduced multicolor cards, albeit only for Z/X Extra.
The color of a card is indicated by the Color Icon, which is located in the upper left side of the card (for cards with old frame) or the upper right corner of the card (for cards with new frame), and is used to determine how the card's Cost is paid and what kind of Resource it provides.
Storywise, a card's color might also denotes from which world that card comes from and/or its affiliation.