Latitude and longitude are the x and y axis on a grid. When you're trying to find a location on earth, you need to graph it, so you can pinpoint the location. There is no grid if there is no longitude and/or latitude lines. Without one of the lines, it would be very hard to graph, which will be difficult in finding locations on earth. But hey, I'm not too sure. I recommend looking at other people's answers too and searching it up.