What causes seasons to occur

The seasons are caused by the tilt of the Earth's rotational axis away or toward the sun as it travels through its year-long path around the sun. The Earth has a tilt of 23.5 degrees relative to the "ecliptic plane" (the imaginary surface formed by it's almost-cicular path around the sun).

Seasons are caused by the tilt of the Earth's axis towards or away from the Sun as it takes its year-long course around the Sun.