Summary

The axis is the line in the middle of the earth. Earth is spinning on it's axis.The axis of it's Tilted by about 23.5 degrees without that tilts the seasons wouldn't change and we will leave in that same seasons.When earth moves around the sun and it's called Revolution.It takes 365days or 1 year  to complete.The earth Orbit is like a regular oval shape or egg shape or an Ellipse. The Seasons north and south of the equator always opposite to each other, so if northernhemisphere  would have summer and other side of the earth would have winter when sunlight comesIndirectly on northern hemisphere the day goes shorter and cold. When the earth is here, sunlight strikes on northern hemisphere Directly so the day goes long and hot it calles summer. Equator is a line a middle of the earth. That's the cause of the seasons.