The world is overlaid with a grid (or sorts, as best can be fit on a sphere) that tells one's location as a coordinate, usually (latitude, longitude). The equator is 0 degrees latitude. The North Pole is 90 degrees north, while the South Pole is 90 degrees South; in between the equator and the poles are 89 other equally spaced latitude lines running horizontally, north and south, appearing parallel on most maps (technically, on a sphere these 'lines' are not parallel, but for casual purposes, if they look parallel, then we'll say they are). Latitude lines are often synonymously known as "parallels".

Longitude lines span the globe from the North Pole to the South Pole, running vertically. There are 360 lines of longitude worldwide. 0 degrees longitude was somewhat arbitrarily set to pass through the city of Greenwich, UK, ages ago. From this all lines of longitude ("meridians") emanate from there. Heading west they count up to 180 degrees, same for the east. The 180 degree longitude is the nominal International Date Line (disregarding the wiggles it takes to conform to national boundaries). For those who care, 0 degrees Latitude by 0 degrees Longitude is located in the Atlantic Ocean off the coast of Africa, roughly south of Nigeria and west of Gabon.

The Degree Confluence Project is a quirky hobby in which people seek to locate and stand on integer points of latitude and longitude. Normally, points between these integer values are broken down decimally or by minutes and seconds. The hobby is GPS dependent and just silly enough to attract my interest. My wife and I did our first in Januray 2005 and we'll add a few more as we see fit and as time permits. It is addictive!