What is the purpose of lines of latitude?

Lines of latitude serve the primary purpose of indicating how far north or south a location is from the equator, which is designated as 0 degrees latitude. Each line of latitude is measured in degrees, with the North Pole at 90 degrees north and the South Pole at 90 degrees south. This geographic coordinate system is crucial for navigation, climate studies, and understanding the Earth's geography.

While lines of latitude play a role in time zones to some extent, the primary basis for time zone determination is more influenced by lines of longitude. Similarly, while latitude can be used for navigation purposes that might involve distance, it does not directly represent distances in kilometers; distances are quantified differently. Additionally, lines of latitude do not mark borders between countries; country borders are generally determined by political and legal agreements rather than geographic lines. Thus, the use of lines of latitude is fundamentally about their function in representing a location's position relative to the equator.