A keyword refers to a collective name of similar effects. Keywords varies in effect, and within community, they are categorized into two different categories, with one that are limited to a certain color, while the other are limited to a certain category of cards, such as Ultimates, but not the color. However, officially, keywords are simply divided into ones that are limited to a certain color, and ones that aren't. Additionally, under such cases, when a keyword is possessed by only one card, even if that card has all six colors, the keyword is considered color-specific.
Many keywords are also the main element of their respective eras, such as Seal being the main mechanic in the God-King era, and Advent the main mechanic in the Advent era. Cards are also often given specific keywords with reference to the card's power in the card lore (such as only The HorseTwelveGodKing Execeed can give the keyword Furious Charge to other Spirits), hence many keywords only appeared once on one card in the entire franchise.
Please refer to the navigation below for more details on each keyword.