Final answer:
Seasons occur due to the tilt of Earth's axis and its revolution around the sun.
Step-by-step explanation:
Seasons occur because Earth's axis is tilted relative to its orbit. As Earth makes a revolution around the sun, direct sunlight moves north and south of the Equator, causing the variation in temperature and weather conditions. The tilt of the Earth's axis also leads to the solstice, where one hemisphere experiences the longest days and the other hemisphere experiences the shortest days.
Learn more about Causes of seasons on Earth