They curve with the curve of the Earth.
The Mercator projection does that.
Each 'meridian' is a line of constant longitude.
Lines of latitude and longitude allows any position on the Earth to be plotted.
longitude
Most maps will show latitude and longitude lines, if not, they're ALWAYS on a globe.
The Mercator projection does that.
The ability of the Mercator projection to allow straight and constant course lines. Or longitude and latitude lines.
The Mercator projection preserves straight lines, making it useful for navigation. It also shows true direction, making it valuable for sailors and pilots. Additionally, it accurately represents shapes and angles near the equator.
latitude?
lines of latitude
Each 'meridian' is a line of constant longitude.
Every meridian of longitude is perpendicular to every parallel of latitude, and every parallel of latitude is perpendicular to every meridian of longitude.
Latitude.
The lines that intercept latitude lines are lines of longitude.
Latitude and longitude
Lines of Longitude
Longitude lines go vertically and latitude lines go horizontally.