Earth
There is more than one planet that has not tilt. The planets are Mercury, Venus, and Jupiter. The planet's also do not have seasons.
The Earth has seasons because it polar axis is tilted relative to its orbit.
Seasons
earth
That's what causes the seasons.
The tilting of the Earth on its axis exposes the planet to different levels of sunlight, this in turn causes temperature variations and results in what is known as seasons.
Mercury, I believe. It's because its axis isn't tilted.
Uranus and Pluto have a tilt and have extreme seasons. Mars, Saturn, and Neptune have seasons that are similar to ours.
Yes, Saturn has a tilted axis. Its axis is tilted at an angle of about 26.73 degrees in relation to its orbit around the Sun, causing the planet to experience seasons similar to those on Earth.
On the contrary, we have seasons precisely because the Earth's axis is tilted.
Mars, earth
As the earth spins on its axis, producing night and day, it also moves about the sun in an elliptical (elongated circle) orbit that requires about 365 1/4 days to complete. The earth's spin axis is tilted with respect to its orbital plane. This is what causes the seasons.