<p><strong>Fig. 1.17.</strong> Lines of latitude and longitude form a global grid system. Any point on earth can be located by specifying its latitude and longitude, including Washington, DC, which is pictured here.</p>

Fig. 1.17. Lines of latitude and longitude form a global grid system. Any point on earth can be located by specifying its latitude and longitude, including Washington, DC, which is pictured here.

Image by Byron Inouye