Although many GPS devices offer coordinate information, it is not always useful to find exactly the locations you want to point out. Coordinates are the most accurate way to find a location, as long as you correctly point the respective values and cardinal points.
Earth Explorer helps you navigate the map, allowing you to point out the coordinates of a street or even the door of a building, which you can send. Or reverse the process, receive a certain address and register, that the map tries to show you the corresponding location.
An interesting aspect that you can consult the map using as a source the world database of images, to navigate observing the real world. Or use different filters, like OpenStreet Map, in which the topology is transformed into a rectilinear blueprint, marking points of interest with symbols, to print as if it were a simplified plan of a place.
The USGS (U.S. Geological Survey) project, a scientific agency of the United States Department of the Interior, was created in 1879, with the main purpose of mapping public lands, registering geological structures and assessing mineral resources. In the future it will involve investigating groundwater, health of the environment, natural disasters, and of course, climate change.