We have seasons on Earth because the axis of rotation of the Earth is not at right angles to the orbital path  The Earth is tilted.

The maximum height of the Sun in the sky is lower in winter because we are tilted away from the Sun as we rotate. It also spends less time in our view as it is lower on the horizon. Therefore the daylight hours are shorter in the winter.

This difference in daylight time is because the Earth is tilted on its axis as it orbits the Sun. In the winter the northern hemisphere is tilted away from the Sun, therefore countries such as ours spend more that half of the time facing away from the Sun (longer nights!). In the summer the northern hemisphere is tilted towards the Sun, therefore countries such as ours spend more that half of the time facing the Sun (longer days!).  In September and March the equinox occurs and daylight hours equal night time hours.

I wish I could take the credit for this Flash graphic but I can't. It appears on so many sites it is hard to tell who wrote it!

Look carefully at the graphics and you can see how the shadow moves across the Nothern hemisphere of the Earth as the year progresses. In midwinter the Arctic gets no daylight for several days and in the summer the sun never sets for several days!