The question is somewhat vague, but I think you may be asking: Why are
different lines of latitude marked with different numbers ?
I'd compare that to the question: Why are different marks on the ruler marked
with different numbers ?
The reason is because both of them are systems invented to help you measure
things. The marks on the ruler help you estimate the length of things that you
place the ruler on, by showing you where a few exact lengths are. And the
horizontal lines on a map or globe help you estimate the latitude of places on
the Earth, by showing you where a few exact latitudes are.
The 'latitude' of a location is its angle north or south of the equator. The 'longitude' of a location is its angle east or west of the Prime Meridian.
Lines of latitude must be used with lines of longitude to help us find the absolute location. Lines of latitude alone cannot determine absolute location.
Each line of latitude is an imaginary east-west circle that connects all locations on Earth that are at the same latitude. Lines of different latitudes are different size circles.
They are the horizontal lines on a map.
a location.
You find the lines of latitude and longitude and find the place that they intersect, which is your location.
latitude and longitude
The lines are what determines the absolute location of a place on the map.
latitude lines measre how far north and south a location is from the what
Latitude and Longitude
Latitude and Longitude :)
Lines of longitude and latitude cross each other and denote the absolute location of the area crossed by the coordinates. Each area on earth has it own absolute location.