Winter is the coldest and darkest season of the year in temperate and polar climates. It occurs after autumn and before spring. The tilt of Earth's axis causes seasons; winter occurs when a hemisphere is oriented away from the Sun. Different cultures define different dates as the start of winter, and some use a definition based on weather.
When it is winter in the Northern Hemisphere, it is summer in the Southern Hemisphere, and vice versa. Winter typically brings precipitation that, depending on a region's climate, is mainly rain or snow. From Wikipedia
