A year is the length of time it takes for planet Earth to complete its orbit around the Sun. This takes the Earth approximately 365 days. 

Our planet travels around the Sun on an elliptical orbit. The Earth is closest to the Sun during January, and furthest away from it during July. 

The picture on the right shows the yearly orbit of planet Earth around the Sun. The Earth on the top shows the planet during spring. On the left, you can see Earth during the summer (when the northern hemisphere is tilted towards the Sun). The Earth on the bottom shows the planet during autumn. On the right, you can see Earth during the winter (when the northern hemisphere is tilted away from the Sun).

The yearly orbit of planet Earth results in the seasons: spring, summer, autumn and winter. The seasons are the result of two factors. First of all, the Earth orbits around the Sun. Secondly, the Earth's axis is tilted at a slight angle. This makes the planet's two hemispheres face the Sun more during different times of the year.