A horizon line is the apparent line that separates the earth from the sky. It is where the sky seems to meet the ground or water, creating a visual boundary. The position of the horizon line can change based on the viewer's elevation and perspective, such as standing on a hill or looking out over the ocean. In art and photography, the horizon line is an important compositional element. It helps to establish depth and perspective in a scene. Artists often use the horizon line to guide the viewer's eye and create a sense of balance in their work, influencing how we perceive landscapes and environments.