Seasons are the periodic changes in the climate, ecology, and biological life cycle observed on Earth, primarily caused by the planet's axial tilt relative to the plane of its orbit around the sun. This gravitational mechanism ensures that different hemispheres receive varying amounts of solar radiation and experience shifts in the angle and duration of daylight throughout the annual cycle. As the planet revolves, certain hemispheres are tilted toward the sun, resulting in periods of increased solar insolation and longer days, which characterize summer. Conversely, when a hemisphere is tilted away, it receives less direct light, leading to cooler temperatures and shorter days associated with winter. These predictable changes in incident energy govern global atmospheric and biological systems.