What does one part of earth experience summer while another part experience winter?

One part of Earth experiences summer while another experiences winter due to the tilt of Earth's axis. As the Earth orbits the Sun, different hemispheres receive varying amounts of sunlight at different times of the year. During summer, a hemisphere is tilted toward the Sun, resulting in longer days and more direct sunlight, while the opposite hemisphere, tilted away, experiences shorter days and less direct sunlight, leading to winter. This axial tilt, combined with Earth's revolution around the Sun, creates the seasonal variations we observe.