1 . Kilometer (km) –
          The kilometer is a unit of length in the metric system, which is the standard system of measurement used in most countries around the world.
          One kilometer is equal to 1,000 meters.
         Kilometers are commonly used for everyday and scientific measurements and are part of the metric system.
2 . Nautical Mile (nmi or NM) –
             The nautical mile is a unit of measurement used primarily in navigation and aviation.
           One nautical mile is defined as one minute of latitude, which is approximately one arcminute of the Earth’s surface.
         The international standard defines 1 nautical mile as exactly 1,852 meters.
          Nautical miles are commonly used in maritime and aviation contexts for measuring distances over water or in the air.