To specify a point in a two dimensional plane we use (X,Y) - X being the location in X axis and Y being the location Y axis.
In somewhat similar manner to specify any position in a Sphere or a Geoid, latitude and longitude are used. However unlike X distance and Y distance, latitude and longitude are actually angles. We will defer the definitions of latitude and longitude for some time.
Since our mother Earth and other planets of our solar family are approximately sphere shaped we use latitude and longitude to specify and identify the location of any place over the surface of earth and other planets. To be more precise, Earth and other planets are more of a form called Geoid rather than a perfect sphere.
Longitude and Latitude are identifiers of any location over the surface of the earth. Just like cities are named so that others can identify and refer them, each location in the earth is also identified with a Longitude and Latitude pair.
Now to look at the Latitude in more detail, Latitude specifies where a point lies on the surface of the earth in north-south position. Parallel lines of constant latitude run towards east and west and form circles. These Latitude lines flow parallel to the Earth's equator. Equator is the line of latitude that separates the Earth in to northern and southern hemispheres.
Latitude values run from 0 degree from equator to 90 degree in the north pole and 0 degree from equator to 90 degree in the south pole.
Longitude specifies the east west position. Meridian or a Line of longitude is a semi circle terminting at south pole and north pole of the Earth.The Prime Meridian is the Meridian that runs through Greenwich, England - which is at 0 degree if Longitude. The opposite semi circle of the Prime Meridian is at 180 degree. Starting from the Prime Meridian the Longitude goes from 0 degree to 180 degree towards west and 0 to 180 degree towards east. At the Equator Each degree of Latitude and Longitude and corresponds to approximately 110 Kilometers or 68.97 miles. As the poles near a degree of Longitude tends to zero. But one degree of Latitude is of the same distance allover - that is 110 Kilometers or 68.97 miles.
Longitude is denoted with symbol λ - Lambda while Longitude is denoted by the symbol φ-Phi.
Let us see some examples: Example 1 The location of New York City is - 40°42′46″ North 74°00′21″ West The Latitude of New York City is 40 degrees 42 minutes 46 seconds north from the Equator. The Longitude of New York City is 74 degrees 00 minutes 21 seconds West from the Prime Meridian.
Example 2 The location of Sydney is - 33°51′54″S 151°12′34″East. The Latitude of Sydney is 33 degrees 51 minutes and 54 seconds south from the Equator. The Longitude of Sydney is 151 degrees 12 minutes and 34 seconds East from the Prime Meridian.
There are 360 degrees in a circle. Each degree is divided into 60 minutes. Each minute is divided into 60 seconds.