Latitude and Longitude Lesson

Taken from: http://life.csu.edu.au/geo/coord.html

Degrees/Minutes/Seconds

The most popular coordinate system is the one that shows standard Degrees/Minutes/Seconds coordinates. Remember that there are 360 degrees, but you can only go up to 90 degrees north or south latitude, or just short of 180 degrees east or west longitude. At the equator a degree of longitude is over 69 miles wide (111 km), so smaller divisions are required for depicting points accurately. The system in use is best remembered like what is used on a clock. Think of a degree as an hour. Each degree is broken up into 60 minutes, each minute is broken up into 60 seconds. A minute is still over a mile wide (1.6 km) at the equator. A second, at .0192 miles, is getting more manageable, but that is still over 100 feet (30 meters). Longitude lines get closer together until they reach the poles, but latitude lines stay the same distance apart all the way to the pole. The distances between latitude lines are easier, always those same figures given above for the equator longitude data. For more accuracy, a degree = 69.1722 miles (111.2981 km), a minute = 1.1528 miles (1.8549 km), a second = 101.45 feet (30.9 meters).
An example of a DMS coordinate is:
N61° 11' 05.5" W130° 30' 10.0"
This Web site will usually present it like this:
7. RAPIDS N61 11' 05.5" W130 30' 10.0" Start of first portage
The first number (7) is the waypoint number. A waypoint is "GPSese" for a point indicated by coordinates in the GPS receiver unit. The word RAPIDS is the waypoint name. The long string of numbers after it is the actual coordinate set. Last is a description or comment of some kind.
The N61 is the number of degrees of North Latitude (N = north). Remember that the degree numbering starts at zero, the Earth's equator. In this case the N61° line runs through the southern Yukon and Northwest Territories, just above the other northern provincial borders. The 11' is the number of minutes (' = minute) north of that. A minute is 1/60th of a degree. The 05.5" is the number of seconds (" = second) north of 11 minutes. A second, like on a clock, is 1/60th of a minute. The same system works for the rest of the coordinate, west longitude part. Remember from the basics above that we're working from a meridian baseline running through Greenwich, England. The east-west latitude lines are parallel and don't cross each other, but the longitude lines all cross at both geographic poles, not the magnetic ones your compass points towards. Also remember that the degree, minutes, and seconds lines get closer together the closer to the poles on any map you are working with.