Meridians are imaginary lines that run from the North Pole to the South Pole, dividing the Earth into sections. They help in determining geographic coordinates, which are essential for navigation and mapping. Each meridian is measured in degrees, with the prime meridian at 0 degrees serving as the starting point. In addition to their geographic significance, meridians are also important in various fields, such as geography, cartography, and navigation. They work alongside parallels, which are horizontal lines that measure latitude, to create a grid system that helps locate places on the Earth's surface.