What are the lines across maps?

Question

what are the lines running east and west across the maps called?

Answer 1

Latitude

Which also Includes Equator...

Answer 2

It seems that you mean the lines of latitude, which do run east to west (or west to east) and measure the location north or south of the Equator, the "waistline" of the Earth.

Some boundaries, though, between countries and/or their subdivisions, run east to west. An example would be much of the USA/Canada boundary.  

Answer 3

The lines represent Latitude and Longitude of a specific point.

Answer 4

Latitude, also known as parallels, as in the 49th parallel, which seperates the U.S. from Canada.

Answer 5

it is not impossible for isobars or isotherms to run east/west across the map and connect lines of equal temperature and pressure in a weather map and  on an ordance survey map they would use height above sea level