Axial tilt is the reason for the season.
This tilt not only accounts for the seasons, it also accounts for the facts that winter solstice in the northern hemisphere corresponds with the summer solstice in the southern hemisphere, the varying length of the daylight phase of a 24-hour period throughout the year, that the sun rises in the northeast in June and the southeast in December, and why the sun’s highest point of the day varies throughout the year.
Today, the sun rises further southeast than on any other day, and sets further southwest. In the northern hemisphere, it's maximal elevation in the midday sky is lower than on any other day, although it will be directly overhead for those living on the Tropic of Capricorn 23.44° S (southern hemisphere).
For those at or above the Arctic Circle (66.56° N), it will be a day of no sunlight, and for those on or below the Antarctic Circle, it will be a day with no sunset.