The Earth’s axis of rotation is tilted relative to the line perpendicular to the plane of Earth’s orbit and ranges between 22.1 and 24.5 degrees. The current value of the tilt is 23.5 degrees and is decreasing.
The period of the obliquity cycle is around 41,000 years.
When the tilt has lower value, the seasons are milder and more comparable to each other. If it has higher value, the seasons are more extreme.