What causes the seasons to change?

The seasons change due to Earth’s axial tilt as it orbits the Sun. When one hemisphere is tilted toward the Sun, it experiences summer, with longer days and more direct sunlight. The opposite hemisphere, tilted away, experiences winter, with shorter days and less sunlight. Spring and autumn occur during the transition, as the tilt aligns more evenly. This cycle repeats annually, shaping climate and ecosystems.