The zodiac in astrology is a 360° coordinate cycle along the ecliptic, divided into twelve equal signs of 30° each. A body’s zodiac sign is determined from its calculated longitude under a declared zodiac convention.
Zodiac signs are not identical to the named astronomical constellations. Constellations are observed sky regions with unequal boundaries; signs are equal coordinate sectors. The shared names come from historical tradition but do not make the two systems interchangeable.
The tropical zodiac anchors its cycle to seasonal points. Sidereal zodiacs use stellar reference conventions and a declared offset. Results can therefore differ even when the underlying celestial position is the same.
Astrology assigns symbolic meanings to the signs. Those meanings are reflective conventions, not scientifically established properties of the sky sectors. See astrology and astronomy for the boundary between computed coordinates and interpretation. The twelve-sign overview then shows how element and modality are used as a declared symbolic vocabulary.
Sources and further reading
The project methodology and pinned Astronomy Engine JavaScript reference document the longitude and tropical-zodiac calculation used here. They do not assign symbolic meanings to the twelve sectors.