The Prime Meridian is the reference line at zero degrees longitude from which all other longitudes are measured on Earth and other planets. It divides the globe into the Eastern and Western Hemispheres and serves as the starting point for the geographic coordinate system. In cybersecurity, the term may be used metaphorically to describe a central reference point or baseline for network configurations, data mapping, or global time synchronization, such as Coordinated Universal Time (UTC), which is based on the Prime Meridian at Greenwich, England.