A day is the time it takes for planet Earth to complete one rotation around its axis. This takes approximately 24 hours.
Our planet orbits the Sun on an almost circular orbit. A complete cycle around this orbit takes our planet approximately 365 days. This is called a year.
The Earth rotates around an imaginary axis that can be drawn between the North and South Poles. This axis is slanted at a constant 23,5 degree angle. This slanted axis, combined with Earth's yearly orbit around the Sun, creates the seasons.
During the summer and winter solstices, the light part of the day is either at its longest or its shortest on one hemispehre. During the winter solstice, the Northern Hemisphere receives the least sunlight. In contrast, during the summer solstice, it receives the most sunlight.
During the spring and autumn equinoxes the day and night are of an equal length everywhere on Earth.
A day is the time it takes for planet Earth to complete one rotation around its axis. This takes approximately 24 hours.