Coordinates
Introduction

Map coordinates may be expressed in different formats (UTM, etc.). The concept of a point location
on earth using latitude and longitude only is presented here. There are lots of other online resources that will assist you with the use of UTM cooridnates. The UTM (Universal Transverse Mercator) is a system of coordinates that describes position on a map. GPS receivers can display
locations in UTM coordinates if that is what you prefer/need. Most maps, especially those for hikers, display UTM coordinates. They are used by Search and Rescue operators and
are even becoming more common in guidebooks. If you want more information pertaining to UTM, check the
How to Read UTM Coordinates at wikiHow. Below is The UTM Grid video provided by wikiHow.
Today I find myself using the latitude and longitude a bit more than UTM.
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Example
Let's use the Bruce Trail as an example. The Bruce Trail crosses the 21st Sideroad [Blue Mountains Map 24, Ed 28.0] in the Beaver Valley section at approximately 44.511710, -80.380860 [same as 44°30'42.2"N 80°22'51.1"W]. Also, there is a recommended parking location at approximately 44.513039, -80.374948. For this example I will use the first set of coordinates (44.511710, -80.380860) that is the approximate location where the Bruce Trail crosses the road.

First number > Latitude
The number 44.511710o is called the latitude and is shown in decimal degrees (no minutes & seconds). The degrees latitude is the location of the given spot north of the reference. For latitude the reference is the equator or 0o latitude. So the spot is 44.511710o north of the equator. Lines of latitude run east-west but measure north or south of the equator. The lines are sometimes called "parallels".
Second number > Longitude
The number -80.380860o is called the longitude and is shown in decimal degrees here. The degrees longitude is the location of the given spot west of the reference. For longitude the reference is the 0o longitude or the prime meridian. The prime meridian is the circular line of longitude that passes through the Royal Observatory, Greenwich in southeast London, U.K. (also known as the Greenwich Meridian). So the spot is -80.380860o west of the prime meridian. Note that the longitude number is shown with a negative (minus) sign in front of it. The negative (minus) sign, in this case, means "west of". Lines of longitude run north-south but measure east (+) or west (-) of the prime meridian.
How to use the latitude/longitude numbers in Google Maps.
Step 1 - Open Google Maps in your browser.
Step 2 - Type (or copy/paste) the latitude/longitude into the Google Maps search form as shown in the image below.
Step 3 - Click the blue search button (magnifying glass).
Step 4 - Google Maps will display the location on the map at that latitude and longitude and display a pin. In the case of this screen capture (below) I had turned on the satellite layer for more detail. The trail passing south to north is faint in the image.

Step 5 - Zoom in to that location (pin) and RIGHT click the arrow and a menu pops up. Click the "What's here?" in the list. Watch the bottom , centre of your monitor screen and you should get a form similar to the one below.

Step 6 - If you are familiar with how Google Maps works, you can use the Google Maps "Get directions" button to create driving directions to the location 44.511710,-80.380860.
Extras
- For more in-depth information about coordinates check websites like Geographic coordinate system at Wikipedia, the free encyclopedia.
- If you own an in-car GPS (e.g. Garmin Nüvi or Garmin Drive Smart series) and have never used latitude/longitude coordinates in the unit, check "Entering Coordinates in Recent Garmin Nüvi GPS Receivers".
- Convert Lat Long to UTM - If you use this online tool, the lat/long 44.511710, -80.380860 converts to UTM Easting = 549210.40 and UTM Northing = 4928896.30 and UTM Zone = 17T.