The line where the Earth's surface meets the sky is called the **horizon**. It is the apparent boundary that separates the Earth from the sky and is visible from any elevated viewpoint. The horizon can vary depending on the observer's height and the landscape, appearing either flat or curved. The visual perception of the horizon has inspired artistic representations in many cultures and serves as a crucial element in navigational techniques. Additionally, atmospheric phenomena can create optical effects near the horizon, such as the bending of light, resulting in beautiful sunrises and sunsets.