A cardinal sign is Aries, Cancer, Libra, or Capricorn. In the tropical zodiac, these signs begin at the equinox and solstice points that divide the cycle into quarters.
Astrological traditions associate the cardinal modality with initiating, directing, or setting activity in motion. That does not mean every person with a cardinal placement is a leader, impatient, or constantly active.
Each cardinal sign has a different element. In the zodiac sequence it is followed by a fixed sign and then a mutable sign.