GPS — a space-based radionavigation system owned by the U.S. Government and operated by the U.S. Air Force — currently provides two levels of service: Standard Positioning Service (SPS) which uses the coarse acquisition (C/A) code on the L1 frequency, and Precise Positioning Service (PPS) which uses the P(Y) code on both the L1 and L2 frequencies.

Access to the latter is restricted to U.S. Armed Forces, U.S. Federal agencies, and selected allied armed forces and governments. The former is available to all, free of any direct user charges.

Whether you’re in the armed forces, the livery service, were traveling to your in-laws’ over the holidays, counting your steps to combat overindulgence during said holidays, or anything in between involving travelling, the chances are very high that you’re familiar with GPS. However, do you know how it came to be? Its trials and tribulations? Its history? Take this quiz to find out.