All planets in our solar system follow an elliptical path. This path is known as an orbit. Earth's orbit is not a perfect circle. If you were to draw the Earth's orbit on a sheet of paper as a perfect circle, the width of the line would be larger than the elliptical path of the Earth.
The Earth's orbit takes about 365 days, this is also called a year. This means that in 365 days (a year) the Earth has gone completely around the Sun. From this we can find that the Earth is actually moving at about 67,000 miles per hour (30 km/sec) through space.
The closest distance Earth is to the sun, or perihelion, is 146 million km (91 million miles) and the farthest or aphelion is 152 million km (94.5 million miles). It takes light (or any other electromagnetic radiation) just over eight minutes to travel from Sun to Earth.
The seasonal changes on Earth are because of the 23.4 degree axial tilt of its rotation and slightly elliptical path around the Sun.
The orbit varies over long periods of time according to the Milankovitch cycles. These cycles are one of the main causes of climate change.