Meridians are semicircles running north to south that connect the poles and are used as reference lines for measuring longitude, while parallels are circles running east to west that are perpendicular to meridians and are used as reference lines for measuring latitude, with the most important being the equator and Arctic Circle. Together, lines of longitude and latitude provide a system to precisely locate any place on Earth.

1. MERIDIANS AND PARALLELS
A series of imaginary vertical and horizontal lines enables us to
identify the exact location of places on Earth.

2. Meridians are semicircles which go from one pole to the other. The
prime meridian, or Greenwich meridian (0º), is the point of reference for
other meridians.

3. Parallels are circles which are perpendicular to the meridians. The equator is
the most important parallel and is the point of reference for the other
parallels.

4. Other important parallels, from north to south, are:
The Arctic Circle

8. Latitude and longitude indicate geographical coordinates: the exact
location of a place on the Earth.

9. Latitude is measured by using the
At the poles they are 90º parallels which start at the equator
(0º).
They are lalitude
north (N) or south (S).

10. They run vertically from 0º to 180º to Longitude is measured by using the
the west (W)… meridians which start at the prime
meridian (0º).
…and 0º to 180º to the east (E).