What combination of factors causes the change of seasons

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

The combination of the Suns revolution and the fixed angle of the Earths axis results in seasonal changes