The lines that travel from west to east and that are highlighted in yellow on this map are __________.

The lines that travel from west to east and are often highlighted in yellow on a map are most likely major latitude lines or parallels. The most significant of these, known as the Equator, divides the Earth into the Northern and Southern Hemispheres. Other important lines of latitude include the Tropic of Cancer and the Tropic of Capricorn, which lie to the north and south of the Equator, respectively.

Latitude lines are imaginary lines that run horizontally around the globe and are used to determine the location of a place on Earth's surface in the north-south dimension. They are measured in degrees from 0° at the Equator to 90° at the poles (North Pole at 90°N and South Pole at 90°S). Lines of latitude are equally spaced and parallel to each other, hence they are also called parallels.

Maps often use these lines as a grid system to help with navigation and location finding. In addition to the Equator, which is at 0° latitude, the Tropic of Cancer (approximately 23.5°N) and the Tropic of Capricorn (approximately 23.5°S) mark the limits of the tropics and are relevant for climate and sunlight-related phenomena such as the solstices, which are the times of the year where the sun reaches its highest or lowest point in the sky at noon.